Party Piece by Steve Hall (Science Fantasy #60, August 1963) begins with some prefatory material about the President of the Midnight Club, Vance Seaton, organising the entertainment for the members’ Xmas dinner.
When the club’s science fiction, fantasy and horror writer members finally meet, and after they have finished their meal, Seaton introduces the first act—a magician called Levito and his daughter/assistant Gloria. After a series of tricks Levito finishes the act with his daughter floating in mid-air: the magician then moves his arms with a complicated flourish and she disappears.
Levito soon makes it clear to Seaton that Gloria wasn’t supposed to vanish, so Seaton gets the other act, a hypnotist, to go on while he and Levito discuss the matter. Seaton then conducts an examination:
Under Seaton’s directions, [Levito] gradually lowered the lighter from a point well above the warped space, where it was clearly visible to Seaton on the other side, until it moved into eclipse behind it. For a moment the flame seemed to wink out of existence, then it abruptly re-appeared and extended itself into a flaring, flickering curtain, as if distorted by some grotesque lens.
“Walk behind it yourself,” instructed [Seaton].
As Levito traversed the full length of the uncanny region, which was about waist high, the mid-section of his body seemed to expand and contract in an eye-wrenching fashion; at times it disappeared altogether, leaving his torso and legs to continue, apparently unconnected.
“Light doesn’t go through it,” muttered Seaton clinically, “it goes around it. I think I know what we’ve got here.”
“What is it?”
“It’s something like a Klein Bottle.” p. 81-82
Further discussions suggest that the enclosed space is a form of three dimensional Möbius strip (I think), and that Gloria may quickly run out of air or overheat.
When the Seaton finally reveals the dilemma to the club members, and asks for suggestions on how to free her, one of them suggests (spoiler) that Levito should move his arms in the opposite manner to unlock the space. However, when the magician tries to do this he cannot remember exactly what he did. Enter the hypnotist, who puts Levito into a trance . . . .
When Gloria finally reappears there is rapturous applause (some of the members think it is part of the act), and she reveals that virtually no time at all had passed inside the space (Seaton observes in passing that you probably can’t distort Space without affecting Time).
This probably sounds like a fairly slight piece, and a contrived one too—but it’s well told, and the hypnotist idea is a neat one.
*** (Good). 3,400 words.