Cartwright and Reed, the plain-clothes men detailed to shadow William Barker, reported nothing suspicious in that gentleman’s movements.  He seemed to be making no effort to secure employment, but, on the other hand, there was little of interest in what he did do.  Again the stone wall of negative action.

Barker spent his mornings in his boarding-house, apparently luxuriating in long slumbers; he ate always at the same cheap restaurant; and his afternoons and evenings were devoted largely to the science of eight-ball pool at Kelly’s place.  There may have been significance in his loyalty to Kelly’s place; but if there was, it was too vague for Carroll to consider.  He merely remembered the fact that Barker was a steady patron of the pool-room near the Union Station, and filed it away with his other threads of information concerning the murder.

Carroll was frankly puzzled.  The case differed widely from any other with which he had ever come in contact.  Usually there was an array of persons upon whom suspicion could be justly thrown; a collection of suspects from whom the investigator could take his choice, or from whom he could extract facts which eventually might be used to corner the guilty person.  In the present case there was no one to whom he could turn an accusing finger.

Of course, he was convinced that William Barker knew a great deal about the crime and the events which preceded it; but Barker wouldn’t talk—­and he, Carroll, had no evidence that enabled him to bluff, to draw Barker out against his will.

The crime seemed to have lost itself in the sleety cold of the December midnight upon which it was committed.  The trails were not blind—­there were simply no trails.  The circumstances baffled explanation—­a lone woman entering an empty taxicab; a run to a distant point in the city; the discovery of the woman’s disappearance, and in her stead the sight of the dead body of a prominent society man—­that, and the further blind information that the suit-case which the woman had carried was the property of the man whose body was huddled horribly in the taxicab.

The woman, whoever she was, had either been unusually clever or unusually lucky.  Minute examination of the interior of the cab had revealed nothing—­not a fingerprint, nor a scrap of handkerchief.  There was absolutely nothing which could serve as a clue in establishing her identity.

And yet, somewhere in the city—­a city of two hundred thousand souls—­was the woman who could clear up the mystery.

Convinced that she was prominent socially, Carroll kept a close eye upon the departures of society women for other cities.  His vigil had been unrewarded thus far.  And the public as a whole waited eagerly for her apprehension, for the public was unanimous in the belief that the woman in the taxicab was the person who had ended Warren’s life.