Five Get Into Trouble by Enid Blyton

A lively holiday adventure follows four cousins—Julian, Dick, Anne and Georgina (who prefers to be called George)—and their dog Timmy when they stumble upon a dangerous scheme while staying away from home; determined and resourceful, the children investigate mysterious goings-on, find themselves in risky situations, and use courage, quick thinking and Timmy’s bravery to outwit the villains and set things right.