Shirley hurried to the entry once more.  This was the only portal through which visitors were admitted to the hospital for the purpose of calling on patients.  He hastened to the uniformed attendant who took down the names of all applicants.  This man, upon inquiry, was a trifle dubious.  True, there had been two Italian women and before them—­yes, there had been a young chap with a green velour hat, and white spats.  He had asked about a Captain Cronin, and when told that a visitor was already seeing the patient, agreed to wait outside.  It had been about five minutes before.  The man was indefinite about more details.  Shirley hurried to the telephone booth in the corridor.  To Headquarters he reported the theft of car “99835 N.Y.,” giving a description of its special features and its make.  This warning he knew would be telephoned to all stations within five minutes, so that every policeman in New York would be on the lookout for the missing machine.  Satisfied, he left the hospital, to walk across the long block to the nearest north and south avenue, where he might catch a surface car.

Suddenly he halted, to mutter in astonishment at a sight which was the surprise of the morning:  it was the missing car standing peacefully on the next corner.

“I wonder what that means?” he murmured, as he stopped to study with great interest the window of an Italian green grocer.  A sidelong glance at the car and its surroundings revealed nothing out of the way.  He retraced his steps to the hospital, wasted ten minutes with a cigarette or two, and still no one seemed to take an interest in the automobile.  Finally he walked up to the car, trying the lock of which he had the only key.  Apparently it had been untampered with, for the key worked perfectly.  Here was Jim Merrivale’s car, a good three hundred yards away from the place where he had locked it to prevent any moving.  He felt certain that keen eyes had him under surveillance, yet he could not observe any observers within the range of his own vision.  It was simply a stupid, quiet slum neighborhood and at the time, unusually deserted by the customary hordes of children and dogs!

What had been the purpose in moving it such a short distance?

Where had it been in the twenty-five minutes since he had left it at the entrance to the hospital?

Why had it been left here, of all places, where he would naturally walk if desirous of taking a street-car?

There seemed no immediate answer to the conundrums.  So, he nonchalantly clambered into the car, after cranking it.  The mechanism seemed in perfect order.  Puzzled, he started to speed up the street, when he observed a white envelope close by his foot, on the floor of the car.

He picked it up, and tearing it open quickly read this simple message.

“To whom it may concern:  It is frequently advisable to mind your own business—­is it not?  Answer:  Yes!”