Dick hurried his steps and called Tom, and then went back to the other hallway, unwilling to leave it unguarded even for a few minutes.  He was just in time to see somebody disappearing down a broad flight of stairs to the floor below.

“Hello! who’s that?” he asked himself, and ran towards the stairs.  When he arrived there he looked down, to see the man going down further, to the ground floor of the hotel.

“The same fellow, I’ll bet all I’m worth!” cried Dick.  “There is that heavy beard!  He must have been watching for a chance to get away!  What a chump I was to let him get out!  I’ve got to stop him!” And he bounded down the stairs three steps at a time.

By the time Dick reached the next floor the man was in the lower corridor of the big hotel.  Here, in spite of the hour, quite a few people were stirring—­ coming in from late suppers after an evening at the play or opera.  The man moved into the crowd and towards the main entrance on Broadway.

“Hi!  Stop him!  Stop that man!” cried the oldest Rover boy, as he, too, gained the lower corridor.  But the man had already gotten out on Broadway.  As Dick came out he saw the fellow run across the street to a distant corner and leap into a taxicab that was empty.  The driver was on the seat and the turnout started rapidly away.

“You’re not going to get away if I can help it,” muttered Dick, desperately, and looked around for another taxicab.  One stood halfway down the block, the driver taking a nap inside.

“Wake up!” exclaimed Dick, shaking the man.  “See that taxi?  I want to follow it!  Don’t let it get out of your sight, if you want your fare and a couple of dollars besides.”

“I’m on!” answered the driver, and leaped into his seat, while Dick got into the cab.  Away they started, in the full glare of the electric lights of Broadway.

The course was downtown, and the first taxicab made rapid progress.  The man inside looked back and when he saw Dick following him, he spoke hurriedly to his driver.  Then the cab turned swiftly into a side street, and, reaching Fifth Avenue, shot northward on that well-known thoroughfare.

“Can you catch that other taxi?” asked Dick, anxiously.

“I can try,” was the grim answer.  “He’s going some, though!”

“Maybe they’ll be held up at some cross street.”

“Not this time in the morning,” answered the driver, “They’ve got a straight road to the Park.”

On and on went one taxicab after the other.  Fifty-fifth Street was passed and still the first turnout kept well in the lead.  But then a big furniture van appeared out of a side street and the cab ahead had to slow down.

“Now is your chance!” cried Dick.  “Run up alongside of ’em!”

His driver did as requested.  But then came a mix-up, as two more cabs appeared, and Dick’s was caught between them.  He looked ahead and saw the man with the heavy beard leap to the ground.