Belfast, 1941. Based on an inspiring true story. 12-years-old Tom Hall (Art Parkinson) is a young teen who occasionally assists his father George, the Bellevue Zoo veterinarian, with the animals. The zoo's newest attraction? A baby elephant, who Tom takes a liking to and names Buster. But as World War II picks up, Tom has no access to his old stomping grounds, nor can he care for Buster. Worse, the Germans have started to bomb Belfast and a decree states all zoo animals must be destroyed in case they escape during a bombing raid. Tom will not have this, and so with the help of his misfit friends, they kidnap Buster. But how long can they keep a growing elephant hidden, especially in time of war?