Thanks for the clarification. The premise raise all kinds of interesting complications and plot twists that you can't cram into a logline, of course. But If you can slip in a few words that it's a temporary swap out without inordinately lengthening the logline, I think it might be a winner.
On suggestion (beyond the scope of the logline) is that as a result of the swap out the antagonist gains a few high cards in his hand (mind actually), to play, too. Better yet, he comes out ahead as a result of the swap in terms of memories,cognitive ability, whatever.
Or at least that mental instability is a side-effect in the brain of the good guy, too, as a character flaw. (An unavoidable hazard for all consciousness's involved in the swap.)
I suggest that because one of the standard m.o.'s for escalating suspense and jeopardy is for the bad guy to get all the luck, all the breaks. The good guys get none; he has to work for everything.
fwiw