Balloon pilot Amelia Wren (Felicity Jones) and scientist James Glaisher (Eddie Redmayne) find themselves in an epic fight for survival while attempting to make discoveries in a gas balloon in the 1860s.

April 6th, 1917. As a regiment assembles to wage war deep in enemy territory, two soldiers are assigned to race against time and deliver a message that will stop 1,600 men from walking straight into a deadly trap.