It tells the imaginative story of a young girl and the Giant who introduces her to the wonders and perils of Giant Country. The BFG, while a giant himself, is a Big Friendly Giant and nothing like the other inhabitants of Giant Country. Standing 24-feet tall with enormous ears and a keen sense of smell, he is endearingly dim-witted and keeps to himself for the most part.

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.