Mistake Inside by James Blish (Startling Stories, March 1948) opens with an astronomer called Tracey, who is about to confront a cheating wife (he is in the process of breaking down a door, gun in hand), suddenly finding himself in another time, possibly Elizabethan England. However, two bystanders identify Tracey as a “transportee” and tell him that he has arrived in the “Outside”, a country ruled during the Fall season by a man called Yeto. Tracey is advised by the two to find a thaumaturgist if he wants to get back to his own world.
The next part of the story sees Tracey wandering around the anachronistic town on his search (during which he is warned that Yeto is arresting transportees), before eventually coming upon a parade. There he sees Yeto (who looks identical to man whose door he was about to break down) sitting beside his wife.
After this event a wizard tells Tracey that to “pivot” back to his own world (the “Inside”) he will needs to find two avatars. One of these is a cat that features earlier on in the story and the other is a man in a top-hat. The latter’s half-visible shade turns up at the foot of Tracey’s bed the next morning, whereupon he tells Tracey that (spoiler) he is in Purgatory, and will need to work out what his failings are or he will end up permanently damned.
The last section of the story sees Tracey find a dog for a boy and, in return, he is given a divining rod which leads him on a chase through the town. Eventually he finds a pair of glass spheres (the avatars, I presume), and is returned to his own world where he crashes through the door to find his wife in the non-carnal company of an astrologer.
If this sounds like a particularly badly written synopsis, it is partly because this story reads like it was made up as the writer went along, and minimally revised. I really should read it again. Notwithstanding this it’s a passable enough Unknown-type tale if you don’t expect the plot to make much sense.
** (Average). 7,750 words.