12-year-old Conor encounters an ancient tree monster who proceeds to help him cope with his mother's terminal illness and being bullied in school.

Two unlikely companions embark on a perilous adventure through the badlands of an unexplored planet as they try to escape a dangerous and disorienting reality, where all inner thoughts are seen and heard by everyone.

Coal Hill School has been a feature of Doctor Who since the first episode, but now we get to see the day-to-day adventures of the students coping with intrusions from space and time.