Just then Fletcher returned with the servants.  The questioning was long and tedious, and developed nothing except that the butler admitted that he was uncertain whether the windows in the library were locked.  The gardener was very obtuse, but finally contributed one possibly important fact.  He had noted in the morning that the back gate, leading into a disused road closer to the bay than the main highway in front of the house, was open.  It was rarely used, and was kept closed only by an ordinary hook.  Whoever had opened it had evidently forgotten to hook it.  He had thought it strange that it was unhooked, and in closing it he had noticed in the mud of the roadway marks that seemed to indicate that an automobile had stood there.

After the servants had gone, Fletcher asked us to excuse him for a while, as he wished to run over to the Greenes’, who lived across the bay.  Miss Bond was completely prostrated by the death of her uncle, he said, and was in an extremely nervous condition.  Meanwhile if we found any need of a machine we might use his uncle’s, or in fact anything around the place.

“Walter,” said Craig, when Fletcher had gone, “I want to run back to town to-night, and I have something I’d like to have you do, too.”

We were soon speeding back along the splendid road to Long Island City, while he laid out our programme.

“You go down to the Star office,” he said, “and look through all the clippings on the whole Fletcher family.  Get a complete story of the life of Helen Bond, too—­what she has done in society, with whom she has been seen mostly, whether she has made any trips abroad, and whether she has ever been engaged—­you know, anything likely to be significant.  I’m going up to the apartment to get my camera and then to the laboratory to get some rather bulky paraphernalia I want to take out to Fletcherwood.  Meet me at the Columbus Circle station at, say half-past-ten.”

So we separated.  My search revealed the fact that Miss Bond had always been intimate with the ultra-fashionable set, had spent last summer in Europe, a good part of the time in Switzerland and Paris with the Greenes.  As far as I could find out she had never been reported engaged, but plenty of fortunes as well as foreign titles had been flitting about the ward of the steel-magnate.

Craig and I met at the appointed time.  He had a lot of paraphernalia with him, and it did not add to our comfort as we sped back, but it wasn’t much over half an hour before we again found ourselves nearing Great Neck.

Instead of going directly back to Fletcherwood, however, Craig had told the chauffeur to stop at the plant of the local electric light and power company, where he asked if he might see the record of the amount of current used the night before.

The curve sprawled across the ruled surface of the sheet by the automatic registering-needle was irregular, showing the ups and downs of the current, rising sharply from sundown and gradually declining after nine o’clock, as the lights went out.  Somewhere between eleven and twelve o’clock, however, the irregular fall of the curve was broken by a quite noticeable upward twist.