At the height of the First World War, two young British soldiers, Schofield and Blake are given a seemingly impossible mission. In a race against time, they must cross enemy territory and deliver a message that will stop a deadly attack on hundreds of soldiers—Blake’s own brother among them.

Neighbors in a block wake one morning to find they have been sealed inside their apartments. Can they work together to find out why? Or will they destroy each other in their fight to escape?