Molly examines her shelf of special things at the back of Mack's stall. She chooses the ‘boss' badge and remembers the day she got it. Mack has to go to the dentist and leaves Molly in charge of the stall. Mrs Stewart wants to buy Euan a thanks you present for helping her, so Molly sells her a toy robot. When Mack arrives back, he tells her that the robot was not for sale and that he was fixing it for Euan. Molly sees the remote control for the robot and has a plan to follow the sound of the robot in order to track it down. Meanwhile, Mrs Stewart is happily shopping around the Big Hub with the robot in her trolley. As the robot starts making loud, alarming announcements, panic spreads amongst the Hubbers. Where is the mysterious voice coming from? Soon Molly and Mack find the robot and reveal what's going on, much to everyone's relief and amusement.