Frida Kempff’s “Knocking” opens with an alluring hook: a foreboding overhead shot of a busy beach that all but screams, “Someone is watching, and they ain’t good!,” Molly (Cecilia Milocco) is napping on a blanket, unknowingly enjoying her last moment of peace as her girlfriend takes a plunge in the glimmering water. Then, a scream. Kempff’s film gets under the audience’s skin almost immediately, but that early power diminishes over the course of

When we next meet Molly, she’s emerging from a psychiatric ward after a prolonged stay. Details of what happened on the beach are unnecessary, but Kempff continually cuts back to that seminal day. Milocco’s performance is strong enough that the audience already understands Molly’s frailty; she’s haunted by something as she re-enters the world.

A (purposely) grating score overlays what seem to be ordinary scenarios, making a train trip feel queasy and wrong.