Harry crossed over to the west side of the city and boarding a Belt Line horse-car, he paid his fare and glanced around. The boy's picturesque costume and fierce big mustache attracted the attention of all the passengers. He returned their curious stares with interest, and looking from one to the other, his gaze finally rested upon a negro sitting in a corner of the car with a big black-enamel valise on his lap. Young King Brady could hardly repress a start. The negro was Sim Johnson! "Great Scott!" he muttered. "It's Mason's friend, the valet. Where is the black rascal going with that big valise? Shall I put the nippers on him? What is he doing over here on West street?" He thought it over. Harry's first impulse was to arrest the man. Cool second-thought restrained him, however, and he muttered softly: "No. I'll shadow him and find out where he is going. It will be time enough to arrest him when I find he's trying to get away." He kept a wary eye on the coon after that. Johnson rode down to the foot of Liberty street and alighted. To Harry's astonishment he saw the darky buy a ticket for Swamp Angel, and then the truth flashed across the boy's mind. "He's going to the very place I'm heading for," thought the boy, "and he must be doing that at the request of Ronald Mason. In that case he's sure to meet the man. What a good decoy duck he will make! By Jove, I've only got to shadow him and he will lead me right to the very place where his employer is concealed. Then we'll be enabled to arrest Mason right away." The coon crossed the river, with Harry on the same boat. Old King Brady met Harry on the Jersey side and Young King Brady told his partner about Sim. A smile of intense satisfaction crossed the old detective's bewhiskered face, and he strode along behind the valet and saw him board the train. The Bradys followed. Shortly afterward the cars started. On the following night they all alighted at Swamp Angel and the negro took to the railroad track and started to tramp in the direction of the swamp where Mr. Dalton's body had disappeared. There was plenty shelter from the negro's gaze for the detectives, and they silently and stealthily sped along in pursuit of their decoy. CHAPTER XI. IN THE QUICKSAND. "Halt, or you're a dead man!" It was a stern command, in a rough voice. The Bradys paused near some rocks and saw two rifle barrels aimed over the top of them, in the hands of two masked men. Hearing the voice, Johnson had come to a sudden stop and glanced around. Just as the detectives were about to reach for the revolvers they carried, the same rough voice sang out, quickly: "Hands up!" The sharp click of the rifle hammers followed. It would have been sheer folly to disobey that command, for the masked men had a bead drawn on the officers. In that lonely place no one would know they got killed. They felt chagrined over the careless way in which they walked right into the ambuscade, and raised their hands.