It was no less than the unexpected acquisition of evidence which seemed as though it must at a stroke establish Countess Alexia’s innocence of the death of Captain Martindale.

“A man has suddenly appeared,” Herriard related, “turned up to-day at Bowyer’s office, who declares that at about 12.30 on the night in question he was walking down Verney Street, and as he passed under the wall of Vaux House he stopped at the west gates to listen to the music which, with the windows open, could be plainly heard. That, as he waited there, his attention was attracted by the sight of a man, evidently one of the guests, who came out upon a low balcony, and, having looked about as though to make sure he was not observed, climbed over the railing and jumped down into the garden. Campion says he then lost sight of the man for a few minutes, but as he stayed on there thinking little of the matter, the man suddenly reappeared, hurried past the gate and came out by the wall door, and then made off quickly towards Piccadilly. Acting upon that evidence young Bowyer immediately set off with Campion to Vaux House. The fellow described exactly where he had stood and pointed out the window through which the man appeared. It was——”

“Of course,” Gastineau interrupted, with his enigmatic smile, “the very window of the room in which Martindale was found dead.”

“Exactly. What do you think of that, my dear friend?”

He was looking eagerly at Gastineau for evidence of his story’s effect; but from the depths of those inscrutable eyes he could draw no certain conclusion. There had been the alert, piercing glitter fastened on him as he told the news, but, beyond a certain almost fierce interest and enquiry, nothing was betrayed.

“A grand piece of evidence,” Gastineau now answered quietly. “Almost too good, too conclusive, to be true.”

“The man is positive,” Herriard urged.

Gastineau nodded, as accepting the statement for what it was worth.

“Why,” he asked, “has he not come forward before?”

“He has been abroad, in South America,” Herriard explained, “and returned only a few days ago. The possible connection of what he saw with Martindale’s death occurred to him last night only, and he went round to Bowyer’s the first thing this morning.”