Book: Gaiman, Neil. Coraline (2002)

Coraline moves into a new apartment with her distracted parents. Curious, smart and very much a kid she gets a little bored. Her father tells her to count, among other things, all of the doors in the house. There are fourteen.

Thirteen doors open and close. One door is locked.

Thirteen doors lead into other parts of the house or out of doors. One door does not.

(  She said to her mother, Where does that door go? )