<p>Charlie Cooper gained a new appreciation for the "mathematical" precision of a great whodunnit story while appearing in the 1950s-set thriller See How They Run.</p><p>The This Country actor plays theatre usher Dennis in the new murder-mystery, which is set amid the glamour of a West End production of Agatha Christie's classic thriller The Mousetrap.</p><p>The discovery of a dead body behind the scenes causes the roulette wheel of potential suspects to spin, while cops played by Sam Rockwell and Saoirse Ronan aim to track down the killer.</p><p>"The challenge is with the writers, I think. It's so formulaic, isn't it — a murder-mystery?" Cooper told Yahoo.</p><p>See How They Run hits UK cinemas on 9 September.</p>
