Rose, the youngest member of the inimitable Casson family, has reached Year 6. SATs are looming. Rose's class has a new - and horrible - teacher called Mr Spencer, who is so intent on reforming his class of miscreants and hothousing them to outstanding marks in these dreaded exams, that he cancels Christmas. Rose and her friends Kiran and Molly have more than a sneaking suspicion that he rather enjoyed doing it too. But Mr Spencer can't cancel the Christmas School Trip and the girls intend to make the most of it. Molly will finally achieve a lifetime's ambition while they're there.