Frank twisted his lower limbs to one side. His assailant was trying with his free hand to reach the pocket in which he had seen Frank place his little cash capital. Frank’s movement disconcerted the would-be thief. He grew angry as his captive wriggled onto one side, holding his pocket pinned up against the car step. “Hi, you, turn over,” growled the fellow. He gave Frank a jerk and then slapped him hard against the side of the head. He managed to thrust his hand into his pocket containing the money. “Ouch!” he yelled, just as his eager fingers touched the roll of bank notes. “Zounds! who did that?” Whack--Frank caught this sound, preceded by the air-cutting whistle of some swiftly-directed object. Whack--whack! the sound was repeated. Frank was free. His assailant had relaxed his grasp. His hands were now busy warding off mysterious blows in the face. Frank darted to one side, his precious savings clasped by one hand. He stared in wonder. Some one on the roof of the front passenger coach was leaning over its rounding edge. He was armed with a jointed piece of iron. This he plied whip-fashion. Twice its end had struck the robber’s face, leaving two great red welts. Then a spry, nimble form dropped from the car roof to the platform. Frank made out a boy about his own age. He was dressed wretchedly, and was thin and weak-looking, and his face was grimed, but he must have had pluck, for, running straight up to the would-be thief, he plied the weapon in his grasp like a flail. A sharp blow made the ruffian roar with pain. Holding a hand to his eye, he retreated down the platform, fairly beaten off. “There’s a police officer,” said Frank suddenly, noticing a man wearing a uniform come running down the platform from the direction of the waiting room. “Oh, pshaw!” ejaculated his rescuer, springing nimbly to the platform of the nearest coach. “Hold on, hold on,” cried Frank--“I want to thank you, I--” But his mysterious friend had sprung across the car platform in a jiffy. He was swallowed up in the darkness beyond. “What’s up?” hailed the policeman, running up breathlessly. “A man tried to rob me,” explained Frank. “Thought I made out a struggle. Did he get anything?” “No.” “Where did he go?” Frank pointed towards the fan-shaped network of tracks melting into the gloom of the switchyards. The policeman ran in that direction. Frank did not accompany him. He did not believe the officer would catch the thief. Besides, Frank was more interested in the strange young fellow who had done him such good service in his time of need. Frank stepped up on the coach platform and peered up and down the sidings near by. His rescuer was nowhere in sight. Frank was sorry for this. The boy had struck him as a hard-luck object. His manifest reluctance against being seen by the officer suggested something sinister about him.