“I could swim out there,” he reflected. “But that would be stupid, if there is anything else. Let me investigate.”

Cautioning the girl to sit still in the launch, he went ashore and found his way to a well-equipped boathouse, with a padlock on the door.

The padlock was not fastened. It was hanging loose in the hasp, and there was a key in it.

“Somebody has been in this place lately,” thought Nick. “Or there may be a man or two in it at this moment. There is only one way to find out, and that is to go in.”

The door was slightly ajar, and the detective pulled it wide enough to permit the passage of his body.

He was in the deep shadow, for the door was at the side, while the lower end of the structure ran out over the water, so that boats could be slipped out of the house into the river down the greased runways without much exertion.

Nick Carter was used to boathouses and boats. He had a boathouse of his own at a country home he owned, but which he seldom occupied for more than three or four weeks each year.

It did not take him long to decide that the house was empty. This was what he had hoped, for he wanted to help himself to a skiff.

The opening into the river, at the end of the runways, was guarded by double doors, bolted inside, but not locked.

Nick selected his skiff—a small, but substantial craft, rather broader in the beam than might have been desired if he had meant to make high speed.