This tricky, unsettling puzzle-box sci-fi tale feels initially familiar, but it doles out its clues at all the right spots, in just the right proportions, until we're left brain-bent and gobsmacked. The feature directing debut of Rob Schroeder -- and the first produced screenplay by writer Conor Stechschulte -- Ultrasound may at first make viewers feel as if they're way ahead of the characters, which is one of its best tricks. But there are little planted clues to let us know that, indeed, things are not as straightforward as they look. Wool (Mr. Mercedes, UnREAL, Mass) is a great pivot point for the story; there's a strange, nervous quality about her performance that keeps things off-balance.
Early on, viewers see her character, Shannon, memorizing dialogue -- words we've heard Glen and Cyndi say to each other. Is she copying down what they said, or is she feeding words to them? Or something else? It turns out that even Shannon doesn't quite know everything that's going on, and the mastermind, Dr. Conners (Tunde Adebimpe), has a dark reason for all of it that packs a wallop. Ultrasound is jumpy and nervy, and it assumes that its audience is smart and demands that attention be paid. It also has no use for any tacked-on chase scenes or fights. Everything here is devoted to the puzzle, and it's very satisfying to see the pieces click together.