Maxwell's ride - M J Trow

It's a busman's holiday for Mad Max, saddled with two precocious nieces who insist he takes them to a theme park. While riding, white-knuckled, the Wild Water, a passenger is killed in the float ahead, and Maxwell and the girls become eyewitnesses to murder. The dead man was an accountant working with CHARTS, a charity organisation sponsoring Leighford High where Maxwell works. With the help of a local reporter, Maxwell delves into CHARTS and begins to unearth a complex web of murky secrets. The corpses multiply as Maxwell nears the end of his search for truth - but will one of them be his own niece?