Laura and her class are going hiking on a field trip to the mountains! The Ham-Hams would like to tag along too, but having missed the bus, they figure it would take them about 3 days of ticky-tickying to get up the mountain. However, Panda introduces his brand new hand-made solution: a Ham-Ham locomotive! All board the new train excitedly. The journey however, is full of difficulties. Not only is the little Penelope, who can’t even reach the pedals, the driver, but also the road ahead is strenuous, confusing, and dangerous.