Dr. Achimov walks out of prison, lifts an energy capsule from the 22nd century's Power Center and leaves the whole city dark. One capsule is left, it has to reach the plant within two hours, and it shatters if anyone uses a time machine or a teleport gadget. So The Doraemons take the slow route, on a steam locomotive driven by Robin, a girl with no patience for Dora the Kid's mouth and none at all for jokes about her grandfather's engine. This is the fifth film built around the Doraemons rather than Nobita.