Chekhov's Gun takes many forms...

I use Chekhov's Gun CONSTANTLY in my writing too. It has sort of gotten to a point of being excessive, actually. That said, I've learned quite quickly that Chekhov's Gun doesn't need to be fired inherently.

Using the classic parable's example: the gun on the mantel can be "fired" in multiple ways.

1. It could be actually fired like the gun it is.


2. It could be an heirloom representing an older generation (akin to using ashes or a gravestone)


3. It could be a symbol for a brewing conflict.

If you want to make the Gun blend in, mention in the same paragraph between 2-4 other Chekhov's Guns. They don't need to be fired in the traditional sense, but just that each of them is a symbol for something, so when people read your story, they just see the intended gun as being "useless junk" unless they've caught on to your use of symbolism thus far in the novel.

Keep in mind that Chekhov's Gun is NOT an infallible law of writing. I am a firm believer in it, but it can be broken periodically specifically to subvert the reader's expectations. Feel free to do so by occasionally not mentioning the gun until it is needed (unless it would come across as an ass-pull), mention the gun (or other guns) and just don't use it (leading your audience to believe they can't be sure when an item will be important, throwing them off), or prepare the gun and attempt to use it only to have it not work and not matter (zigzagging expectations).

Chekhov's Gun is just a trope. Don't assume you have to always play it straight. Play with it a little to fit your desired situation. Sometimes, you need to play with other guns so people won't see when you're ready to fire this one.

As for your specific gun, though, you can solve this situation simply by having him pass by the door to the basement with an aged piece of paper still taped to the basement door saying "Do Not Enter!" or "Keep Out!" It really doesn't have to be anything major. It can be an organic moment like he sits down in the kitchen and that door is visible across the way. He can't help but to notice it, but by dismissing it immediately and not mentioning it at all for a while, the reader will forget it if you let them.

PSA: Don't play with guns, kids!

There are certain things that are traditionally kept in basements: main breaker panels, furnace, hot water tank etc. Mention of one of those can imply the basement. If the lights flicker, the MC can write a note to the other asking about the fuse box and be told that he’ll take care of it later.

Depending on the age and style of the house in question, there could be a cellar hatch in the floor - usually the kitchen - something your MC would not only notice, but probably stand on while getting his cup of coffee.

In one house I used to own, there was a complicated system of rooms that had been dug out from beneath the house in three separate stages. One was a small cold storage room (ideal for trapping curious MCs in), there was a main furnace room with workbench, and oddly what looked like a rec room - also useful for storing curious characters. Two of these had doors and the level was only accessible through a cellar hatch in the back porch. Move a BBQ over that and anyone beneath is staying there.

Your MC could stub his toe on the hatch or just wonder if it were an old enough house to have once been heated with coal.

If the hot water runs out or the house starts to get cold, thoughts of what is normally stored in basements would be natural enough.

Personally, I would probably choose something like a cellar hatch that, to protect the edges of both the hatch and the floor, has a frame. Ours had a brass one around the linoleum. MC could have a geometric taste in decor and appreciate that detail of the house.

One house had a beautiful old cherry door - rather narrow - that was often mistaken for a cellar door but was for a closet. Such a door could attract the MC’s attention in his exploration, he thinks it is a closet but no - just basement access. Since he wants a place to hang his coat, he is disappointed to find it’s not a closet.

The way to foreshadow something without giving it away is to use it to tell something else. If you tell there is a gun, people think it might be used to shoot someone. If you tell that a person is a police officer who takes his gun off when he comes home? Well, somebody is still probably going to get shot and you are foreshadowing it. But what if the reason you mention him taking the gun off is because years ago he accidentally shot an innocent man in the line of duty and every single time he takes the gun off he remembers that. And you can see that going thru his mind.

In your particular case since they communicate by letters, the easiest way is to link it to something communicated in those letters. Not that you need to specifically describe or even mention the letter.

So there is some reason that door is locked. And the other person does not want the MC to know that reason. And he does not want the MC to think about it and try to find out. So he will provide a perfectly reasonable reason why he needs a locked basement and why it would be a problem if the MC went in.

The supplied reason would almost have to be related to work, so that it is serious enough to justify the locks and the MC thinks the other person is stuck with it and cannot make exceptions. And it is perfectly normal and totally non-suspicious to mention what people do for a living when you first mention it. And it would be natural to mention what silly things are involved with that work. I mean, a perfectly secure work room in the basement you cannot let anyone else in? This guy sure is committed to his work.

Some hobbies might also justify the locks. Say if you have a valuable collection of some sorts in there. This is not always a good choice because people will expect you to show off the collection when you have the chance. But what if there never was such a chance before things start happening and the other character knew that in advance?

I would hide the basement but not the locked door.

A coded padlock on a door inside a house is really weird, and the sort of thing someone would notice and probably comment on. If the MC has a guest, the guest could ask about it and the MC might reply "I don't know. He only opens it when I'm not around."

Mentioning the existence of this door will not lead your readers to think "oh that's a basement and the MC will get trapped there." Not most readers anyway. It would make me think "the housemate has a secret."

In this case, you're foreshadowing the secret, in the sense that we expect to find out what it is. You can drop other hints as to what the secret is and also throw in some red herrings. For example, if the MC knows or suspects the housemate sells drugs, the reader (or MC) might think the locked door could be to a room where drugs are stored or packaged/made. You don't have to make that connection obvious, but a couple hints like that will allow the reader to speculate.

At some point, the MC discovers what's behind the mystery door. And boom is trapped there. It may or may not take more time to discover the secret (in part that depends on how dark the basement is or how obvious the stuff in there is).

A basement is a common feature in a house (mostly in areas with cold winters) and in retrospect the fact that the locked door led to a basement will be fairly obvious, even if it wasn't considered beforehand (it could be a closet or pantry or spare bedroom).

Don't over-Chekhov

Some things appear in the narrative only to set the scene - there can be a gun on the mantelpiece which is never fired if we are going to draw some inference from it. If you're going to take out every reference to every object or decor which doesn't materially return in the plot, then you've picked a very sparse mode with little atmosphere.

Consider the opening of Jane Eyre - it is set in a house to which we don't return, and she sits by a window which never later matters, and looks at pictures which never later change the course of events. The details set the scene, they don't define the later plot.

Chekhov mentions a gun because a gun is a significant thing, so there being a gun is a thing to notice. It's not Chekhov's pantry, or Chekhov's curtain.

The reader fills in detail as they're given it

Nick pushed open the shabby front door, ancient hinges protesting, and peered into the house beyond. A picture of faded colours and decay met his eyes, and a musty scent invaded his nose.

Nick is walking into a house, which we guess from the 'front door' reference, and it's a house he doesn't know, which we guess from his tentativeness and noticing the colours and smell. I have not described the roof, nor the rooms, nor anything else, but we infer normality unless otherwise told.

Let your narrative narrate

If your MC was telling you the story, how would they tell it? When would they mention the basement?

I wandered through from the kitchen past the basement door which I was never allowed to open for some reason, another of Jake's little rules.

Jen might mention the basement door in the context of moving about, or of chatting about Jake's foibles, or just of describing the house in detail when we first meet it. Or not at all until something happens and we need to know about it:

A scraping sound from the corner of the kitchen jolted Jen from her thoughts, and she realised it was coming from behind the basement door. She had never been allowed to open it, and Jake had put some padlock on it so she had never been able to investigate it. Occasionally she had wondered what nerdy collection he might be hoarding down there, but had never seen him go near it.

The scraping sound came a second time, and the hairs stood up on her neck. She put down the sandwich and eyed the padlock.

If you don't want your reader to think that an object has significance later, make its appearance natural to the situation.

Example:

gun

If you want there to be a gun, and you don't want it to appear out of nowhere later, but you don't want the reader to know that it will be used later, you need a situation in which a gun is normal. For example, it can be part of the outfit of a policeperson, it can be a tool for a hunter, it can be part of a collection of antique weapons, and so on.

When the movie opens with a father and his son coming home from a weekend out hunting, and we see the man put the gun away along with his other gear, while the movie focusses on the relationship between father and son, we will know that there is a gun but assume that it has no more relevance than the tent or the hiking boots, because its presence is not emphasized and not out of context.

I'm not giving you a solution to your specific problem, because I don't want to take your question as asking what to write (which is off topic).

In your specific case, I don't think it is possible.

Your case is not a case of Chekhov's gun, as Zeus mentioned. Your case is that you want to have a twist that surprises the reader, but you also want to foreshadow some crucial details of the twist.

Not only should the reader know that there is a padlock, the reader should also know that the padlock has a combination that is only known by the housemate. At the same time, you want to write it in a way that the reader will never question whether this will become important later on.

I frankly think this is impossible. The plot-important objects are too well-established in fiction. Any fiction-savvy reader will immediately know that a locked basement always equals bad news, especially if it's locked with a padlock, which implies high security and secrets even more than a normal lock does.

The obvious choice to confuse the reader would be the use of red herrings, i.e. other potential clues to mislead the reader, which are maybe not related to the house at all. If the reader thinks the story is heading in a certain direction, you can surprise them by suddenly going back to the locked basement that was introduced way earlier. But this depends strongly on the execution, and more importantly, it's practically the opposite of Chekhov's gun.

As others have explained, Chekhov's gun is a bit of a red herring in this context. I think what you want is to be fair to the reader, not to make it seem as though you pulled a convenient basement out of your ass late in the day to get you out of a plot hole.

What I would suggests is to scatter the information about the basement and padlocks throughout the narrative, rather than lumping it all in at one go. In this instance you could break it does into elements such as

• if the house isn't remote, a character might be in a neighbouring house of similar design, which has a basement. It only needs to get mentioned in passing, someone says somehting like, 'excuse me I just need to pop down to the basement to empty the dryer'.


• the padlock could be foreshadowed with comments about the losability of keys, someone gets their bike stolen because they dropped the lock key and Housemate remarks that's why he never relies on keys for anything really important to him.


• The forbidding of access can be established as part of the housemates character not to let people have ready access to his spaces. You could even have him making a point about locking his own room with a key, which might lead an attentive reader to wonder what the housemate really values if he trusts his room to a key-lock.... leading to a satisfied 'Ahhh, I see moment for those readers when he locks the MC in with a combination padlock.

Describe the container of the gun instead.

Let's say that gun has to be in a room. When you are at the point of describing the room's content, just also describe a box, the size enough to fit your desired gun.

That way, you did not directly described any gun and you got your desired effect: the reader that is paying attention and it's very involved in the evolution of your storyline may assume that the box may contain a gun, while others will not thing anything special about it.

Guns aside, you could use this tactic to indirectly imply the existence of anything you want, without making anything obvious. Finding an object around that normally sits in a basement would be an option in your specific case.

The Chekhov's gun principle basically states that details not relevant to the story should be left out. It literally means that if you make note of a gun in the room, that at some point the gun will be fired.

The basement does not need to follow that rule exactly. A gun is obvious. A basement door is not. Just because the basement exists, does not need to mean that anyone would be locked inside of it. You could use misdirection to have the reader guessing what is going to happen with the basement. The main character could hear strange sounds, or smells. The power could go out, and the home owner would need to go down there to change a fuse or for some other reason. All the reader really needs to know is that this basement exists at some point.

The padlock is easy - have the housemate ride a bike and have them chain it up for security when they go somewhere. In this case you don't even need to mention the padlock - having the roommate be commute by bicycle will be enough to imply that they may have things like a bike chain, a padlock, a helmet, a tire pump, etc.

An alternative approach might be to use it twice:

• Show the gun early on.




• In the first act, have a character fire it, for some minor plot reason.




• Don't mention it again until near the end, and then have a character fire it a second time.

(TVTropes calls this Chekhov's Boomerang.  Warning: TVTropes!)

This hides the gun in plain sight, while preserving (some of) the surprise.  Savvy readers are likely to think that the gun has served its purpose after its first use, and then forget about it, so there's a good chance they won't be expecting it to reappear.

It may help if you can make the gun seem completely ‘used up’ after its first firing — all its possibilities exhausted, and neatly filling that plot point — so that readers are likely to dismiss it.  And also if you don't make too much of that first firing, perhaps making the ensuing plot development into a distraction.  That should help to make its reappearance more surprising.