Another dependable mystery adventure with Julian, Dick, Anne, George -- and Tim the dog, and as always the chipper tots confound the adults -- which may account for the success of these books. The children spend Christmas at Kirrin Cottage, where they first met their cousin Georgina (who insisted on being called George) and had a mighty adventure (Five on a Treasure Island -- 1950). This time George with the help of Tim discovers the awful truth about a seemingly genial tutor hom the others like, and when some valuable pages of their uncle's scientific work are stolen the children spring into action. Secret tunnels, Tim's snarl, and a chase do the bad guys in. Again the airy British speech both aids and hinders the action, but withal a cheery business.