Welcome to the greatest murder ever staged! It is the West End of London in the 1950s, and plans for a movie version of a smash-hit play have come to an abrupt halt after a pivotal member of the crew is murdered. When world-weary Inspector Stoppard (Sam Rockwell) and his eager rookie sidekick, Constable Stalker (Saoirse Ronan), take on the case, the two find themselves thrown into a puzzling whodunit within the glamorously sordid theatre underground. The more they investigate the mysterious homicide, the more they realize that they do so at their own peril.