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. A horticulturist named Ivor Leaf brings a unique, rare plant to the Underground. When people touch the plant, it gives them purple hands. Ivor explains that the effects are not permanent and everyone is relieved.