Welcome to a story of radioactive ice cream, monsters in the sludge, and two superheroes who spend more time chatting than actually saving the world...

When everyone's favourite stately home becomes haunted by a terrible swamp monster (who seems to love kidnapping cows), Peng and Spanners: The Swamp Thing! are called in to investigate the swamp and unblock the mystery. Luckily, the robot dog Secret Business is prepared to hang out in a miniature submarine and snoop on suspicious conversations between anyone who has an interest in causing mischief. Meanwhile, Peng and Spanners interview suspects, debate everything, and try to get their hands on more pizza...