Rex's parents have split up, he's about to make the daunting move to secondary school, and to make matters worse he has to spend his summer holiday on a remote and rainy Irish island - with lots of unruly sheep for company. The only upside: he'll be staying with his strange and brilliant Uncle Derm. Then Rex discovers Uncle Derm is about to execute his most hair-brained plan yet - to rob the island's travelling bank!Like the local legend of medieval Pirate Queen Grace O'Malley, Uncle Derm plans to redistribute the money to local needy causes on the island.