Roger is a older mouse who is looking for calm after being threatened by cats most of his life. He is very resourceful and can do anything with his trusted needle and thread and a backpack filled with gadgets.
Theo is a younger mouse, untested, but filled with optimism. He lives on the train where he was born and raised with his small family. One day, while exploring the different cars of the train, he stumbles upon Roger and his workshop. In Roger, he finds a friend and mentor. Always on the sidelines, he is confident and eager to test out his feet. He is sure he can stay one step ahead of Roger in his favorite game, "hide and seek!"