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.