THE HARDY BOYS SERIES By FRANKLIN W. DIXON Illustrated. Every Volume Complete in Itself The Hardy Boys are sons of a celebrated American detective, and during vacations and their off time from school they help their father by hunting down clues them- selves. THE TOWER TREASURE A'dying criminal confessed that his loot had been secreted " in the tower." It remained for the Hardy Boys to clear up the mystery. THE HOUSE ON THE CLIFF Mr. Hardy started to invest- igate and disappeared ! An odd tale, with plenty of excitement. THE SECRET OF THE OLD MILL Counterfeit money was in circulation, and the limit was reached when Mrs. Hardy took some from a stranger. A tale full of thrills. THE MISSING CHUMS Two of the Hardy Boys' chums disappear and are almost rescued by their friends when all are captured. A thrilling story of adventure. HUNTING FOR HIDDEN GOLD I n tracing some stolen gold the trail leads the boys to an abandoned mine, and there things start to happen. THE SHORE ROAD MYSTERY Automobiles were disap- pearing most mysteriously from the Shore Road. It remained for the Hardy Boys to solve the mystery. THE SECRET OF THE CAVES When the boys reached the caves they came unexpectedly upon a queer old hermit. THE MYSTERY OF CABIN ISLAND A story of queer adventures on a rockbound island. THE GREAT AIRPORT MYSTERY The Hardy Boys solve the mystery of the disappearance of some valuable mail. WHAT HAPPENED AT MIDNIGHT The boys follow a trail that ends in a strange and exciting situation. WHILE THE CLOCK TICKED The Hardy Boys aid in vin- dicating a man who has been wrongly accused of a crime. FOOTPRINTS UNDER THE WINDOW The Smuggling of Chinese into this country is the basis of this story in which the boys find thrills and excitement aplenty. GROSSET & DUNLAP, Publishers, NEW YORK