It was pitch dark, but we plunged ahead over fields and through little clumps of trees, around hedges, and over fences.

There was no stopping, no cessation of the deep baying of the dog.  Cherry was one of the best and most versatile that the police had ever acquired and trained.

We came to the next crossroad, and the dog started up in the direction of the main road, questing carefully.

We had gone not a hundred feet when a dark object darted out of the bushes at the side of the road, and I felt myself unceremoniously tumbled off my feet.

Garrick leaped aside, with a laugh.

“Dillon,” he shouted ahead at the top of his voice, “one of the Airedales has discovered Marshall.  Come back here.  Lie still, Tom.  The dog is trained to run between the legs and trip up anyone without a police uniform.  By Jupiter—­here’s another one—­after me.  Dillon—­I say—­Dillon!”

The commissioner came back, laughing at our plight, and called off the dogs, who were now barking furiously.  We let him get a little ahead, calling the Airedales to follow him.  They were not much good on the scent, but keen and intelligent along the lines of their training, and perfectly willing to follow Dillon, who was trusting to the keen sense of Cherry.

A little further down, the fugitives had evidently left the road after getting their bearings.

“They must have heard the dogs,” commented Garrick.  “They are doubling on their tracks, now, and making for the Ramapo River in the hope of throwing the dogs off the scent.  That’s the game.  It’s an old trick.”

We came, sure enough, in a few minutes to the river.  That had indeed been their objective point.  Cherry was baffled.  We stuck close to Dillon, after our previous experience, as we stopped to talk over hastily what to do.

Had they gone up or down, or had they crossed?  There was not much time that we could afford to lose here in speculation if we were going to catch them.

Cherry was casting backward in an instinctive endeavour to pick up the trail.  Dillon had taken her across and she had not succeeded in finding the scent on the opposite bank for several hundred yards on either side.

“They started off toward the southwest,” reasoned Garrick quickly.  “Then they turned in this direction.  The railroads are over there.  Yes, that is what they would make for.  Dillon,” he called, “let us follow the right bank of the river down this way, and see if we can’t pick them up again.”

The river was shallow at this point, but full of rocks, which made it extremely hard, if not dangerous, to walk even close to the bank in the darkness.  “I don’t think they’d stand for much of this sort of going,” remarked Garrick.  “A little of it would satisfy them, and they’d strike out again.”

He was right.  Perhaps five minutes later, after wading in the cold water, clinging as close to the bank as we could, we came to a sort of rapids.  Cherry, who had been urged on by Dillon, gave a jerk at her leash, as she sniffed along the bank.