This time, Germany is the destination of Emily and Alexander, two mice who love to travel. They visit their cousin Nina in Leipzig, who makes mouse toys, and also meet the famous toy manufacturer Richard Steiff. He has just invented his latest toy: a teddy bear! All the children immediately take the cuddly bear to their hearts, especially the spoiled neighbor boy Heinz, who desperately wants the bear. When the bear suddenly disappears, Emily and Alexander immediately start investigating.