A scant arm’s length separated him from Thompson.  Thompson bridged that gap with his feet still on the running-board of the roadster.  He moved so quickly that the chauffeur had no chance.  He did try to slide out from behind the wheel and his fist doubled and drew back, but Thompson’s work-hardened fingers closed about his neck, and the powerful arms back of those clutching hands twisted the man out of all position to strike any sort of blow.  He yanked the chauffeur’s head out over the side of the car, struck him one open-handed slap that was like an earnest cluff from a sizable bear, lifted again and banged the man’s face down on the controls on his wheels, then pushed him back into his seat, limp and disheveled, all the insolent defiance knocked out of him.

Thompson stood on the running board, panting a little, the blaze of a quick anger bright in his blue eyes, and he became aware of two men in the rear seat of the gray car, gazing at him in open-mouthed astonishment.  One was fat and long past forty, well fed, well dressed, a prosperous citizen.  The other was a slim youngster in the early twenties, astonishingly like his older companion as to feature.

Thompson looked at them, and back at the cowed driver who was feeling his neck and face with shaky fingers.  Just then three things happened—­simultaneously.  The traffic whistle blew.  The younger man opened his mouth and uttered, “I say—­” Sophie plucked at Thompson’s arm, crying “Sit down, sit down.”

Thompson was still fumbling the catch on the door when they swept over the cross street and raced down the next block.  He looked back.  The gray car was hidden somewhere in a rolling phalanx of other motors.  The traffic had split and flowed about and past it, stalled there doubtless while the red-faced chauffeur wiped the blood out of his eyes and wondered if a street car had struck him.

“Do you habitually reprove ill-bred persons in that vigorous manner?”

He became aware of Sophie speaking.  He looked at her.  So far as he could gather from her profile she was quite unperturbed, making her way among the traffic that is always like a troubled sea between Third and the Ferry Building.

“No,” he replied diffidently.  “I daresay I’d be in jail or the hospital most of the time if I did.  Still, that was rather a rank case.  I’m not sorry I bumped him.  He’ll be civil to the next woman he meets.”

What he did not attempt to explain to Sophie, a matter he scarcely fathomed himself, was his precipitancy, this going off “half-cocked”, as he put it.  He wasn’t given to quick bursts of temper.  It was as if he had been holding himself in and the self-contained pressure had grown acute when the insolent chauffeur presented himself as a relief valve.  He felt a little ashamed now.

Sophie swung the roadster in to the curb before the express office.  Thompson got out.

“Good-by till this evening, then,” he said.  “I’ll be there if the police don’t get me.”