It's 1900. Thirteen-year-old Issy McKelvie leaves school and starts her first job - very reluctantly - as a maid in an undertaking establishment. She thinks this is about as low as you can go. But there's worse to come. Issy becomes an unwilling rat-catcher when the plague - the Black Death - arrives in Australia. Issy loathes both rats and her father's four yappy, snappy, hyperactive rat-killing terriers. But when her father becomes ill it's up to Issy to join the battle to rid the city of the plague-carrying rats.