Young reporter-in-training Kate and her mouse-accomplice Rupert are on board a train, to visit Kate's mum in the Arctic. But as soon as the train departs, mysterious things start happening. A packet of ginger nuts goes missing. A collection of gymnastics trophies are stolen And some ancient scrolls disappear. Fellow passenger Madame Maude seems the most likely culprit, until a surprising, and delicious, twist turns the whole investigation on its head.