After stumbling upon a portal to the past in the ruins of an old Yorkshire farmhouse. Tom, a troubled schoolboy, is whisked back to the time of the Second World War. With a lovable sheep dog named Tess as his only guide, he meets Sam Wheeler, a kindly farmer (Tom Wilkinson) and May. an orphaned evacuee about his own age. Learning to cope with the dangers and difficulties of life in this time helps Tom come to terms with his own family problems. Back in the present, he discovers something terrible has happened to his friends just a few days after his visit, and he is desperate to get back to the past to save them... even if doing so has consequences he could never dream of.