Mousehole, by Stuart Harbour appeared in the Winter 1954 issue of Fantastic Story Magazine. It can be read here at Archive.org.
Mousehole is one of those stories that takes a sort of cutesy approach to weird horror. The premise is Lovecraftian, the outcome grisly, and the results droll.
The nutshell of the story is a mad scientist creates a dimensional rift that results in the shrinkage of matter passing through it. It’s more a magic hole than a scientific one, but hey. Anyway, the mad scientist dies and his relatives inherit the house.
The husband is an abusive jerk who treats his wife like crap. Hubby is certain mad scientist has stashed a fortune somewhere in the house. Wife thinks she’s going crazy hearing noises coming from a room or corridor which is inaccessible and shouldn’t really exist [one of those “I think this locked door inside is this locked door that opens outside, but it doesn’t fit the house’s blue prints”].
They check out the secret room, which actually opens out to a mouse hole; the cat reaches in and tears the husband apart. Kitty gets pets.
Funny thing about this is I’ve seen almost exactly this set-up in an OSR dungeon written by James Hutchings. In that one, one floor of the tower has two doors that as you go through one, you come out the other in the same space, only smaller/larger depending on the direction you went. It’s a neat trick that you could do a few interesting things with in game, even though it had no real bearing on the adventure beyond an “ain’t it neat?” set-piece.
Again, this was a cute and fun story, offering a light and insubstantial take on weird horror. Maybe it forebodes ill tidings of weird fiction becoming the realm of cat ladies and stories of revenge on ‘muh oppressive patriarchy’, but it’s hard to care too much; at least it’s not bludgeoning readers with its thinkery the way some of the pulps were by the 50s [I’m looking at you, Damon Knight, Ray Bradbury, and several other schmucks I’ve reviewed here!]