Kingsman star Colin Firth and Dr. Strange actor Benedict Cumberbatch are in for a harrowing war as Sam Mendes’ WWW-set film 1917 drops its first trailer today.

The film follows the life-and-death journey of two young British soldiers who are given a mission by the army’s higher-ups. They need to search for one of the two young soldiers’ older brother within the day and stop them from carrying out their orders. This is because they are unknowingly on to a path of no return. The older brother’s mission will become a massacre if the two young soldiers don’t stop it in time.

“They’re walking into a trap. Your orders are to deliver a message to call off tomorrow morning’s attack. If you don’t, we will lose 1,600 men — your brother among them,” Firth lays the truth down on the pair. The trailer then cuts into a montage of the two’s intense journey through the bloodied battlefield. Amidst the bombs going off and gunshots, Firth’s voice rings: “If you fail, it will be a massacre.”

The production of this film started shooting back last April, with them picking out locations in Scotland and England.

Under DreamWorks Pictures and Universal Pictures, this war thriller film will have its initial release this coming December 25.