Quicksand

A British psychiatrist in a deadening job and a deadening marriage gets a mysterious patient; a petite young woman who speaks an unrecognizable language and is unfamiliar with the common objects, sights, and behaviors of normal life, yet who is able to quickly and easily cripple or kill a large man with her bare hands when she feels threatened. He feels more than professional concern for the woman, who he believes is not actually mentally ill but is in fact a more unusual case.