Sophie Thatcher and Jack Quaid star in a comedic thriller that’s better with dark twists than it is with big ideas. Photo: Warner Bros. For maximum appreciation of its first act, Companion should ideally be gone into cold. But any attempt to preserve the sanctity of that experience also renders the movie impossible to write about, since what’s hidden behind that first big bend in the plot isn’t a twist so much as it is the premise — so consider yourself warned. Companion , a devious dark comedy