Doctor Dog, the Gumboyle family's favourite pet and their very own trusty physician, is having a well-deserved rest on a tropical island. Until, that is, the Gumboyles turn up and need rescuing from a variety of nasty holiday ailments! With the help of the long-lost herbal scientist Professor Dash Hund, Dr Dog uses herbal remedies to soothe mosquito bites and sunburn, settle a nasty case of motion sickness and draw out a big juicy boil. But the Gumboyles have one problem that even Dr Dog can't solve. A hungry and highly dangerous plant is lurking in the campsite and it could strike at any moment . . .