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. The trains are excited to see their old friend Brooklyn, especially as he's bringing US athlete Rocky Two Shoes with him for the big race. Ernie enters Farmer Sprout's organic vegetable competition.