Archie loves to draw. He often goes to the Art Gallery to make copies of the beautiful paintings there. One evening he finds himself locked in the gallery after it has closed. It should be easy to get someone to let him out. But Archie is not the only person in the gallery that night. There are other visitors - and they are up to no good. When he realises there's a robbery happening, Archie knows it's his job to stop it.