So he moved on, slowly, because it was necessary to watch the trail closely. He reckoned that he had been following the tyre tracks for an hour and a half when a shadowy outline ahead told him that he was within a few yards of some building. His pulse moved a beat quicker as he discerned a yard or two in front of him ghostly tall iron gates. They were solid enough as he reached out to touch them and a second’s investigation told him of the padlock with which they were secured.

As he stood considering his next move there was a quick yelp. Then a huge form magnified by the mist to gigantic dimensions, hurled itself with a low snarl at the bars. Lucky, too, it was for Labar that the gate stood between him and the Alsatian. The gate shook with the impact, and swiftly and silently as a shadow Labar leapt away.

He groped his way round the wall that surrounded the grounds while the dog whimpered and snarled. His wits were moving fast. He had recognised a breed of dog much favoured for police purposes, and he knew that unless he took precautions right away his discovery was inevitable.