CGI animation. Ernie, controller of International Underground, is always on hand to help his friends and to get passengers to their destinations safely. He is helped by trains Victoria, Bakerloo, Circle, Jubilee, the twins Hammersmith and City and Ernie's friends Millie and Mr Rails. Mr Movie Jones visits Ernie to see if Sea Shell Bay could be a location for his next film. Ernie and Mr Rails are keen to give the right impression, but clearing up Sea Shell Bay is difficult.