She threw herself back in her chair with a dejected face.  “Oh, as for that,” she cried, wearily, crossing her hands, “before you and Hilda, who know all, what need to prevaricate?  How can I believe it?  We understand how it came about.  That woman!  That woman!”

“The real wonder is,” Hilda murmured, soothing her white hand, “that he contained himself so long!”

“Well, we all know Hugo,” I went on, as quietly as I was able; “and, knowing Hugo, we know that he might be urged to commit this wild act in a fierce moment of indignation—­righteous indignation on behalf of his motherless girls, under tremendous provocation.  But we also know that, having once committed it, he would never stoop to disown it by a subterfuge.”

The heart-broken sister let her head drop faintly.  “So Hilda told me,” she murmured; “and what Hilda says in these matters is almost always final.”

We debated the question for some minutes more.  Then Mrs. Mallet cried at last:  “At any rate, he has fled for the moment, and his flight alone brings the worst suspicion upon him.  That is our chief point.  We must find out where he is; and if he has gone right away, we must bring him back to London.”

“Where do you think he has taken refuge?”

“The police, Dr. Sebastian has ascertained, are watching the railway stations, and the ports for the Continent.”

“Very like the police!” Hilda exclaimed, with more than a touch of contempt in her voice.  “As if a clever man-of-the-world like Hugo Le Geyt would run away by rail, or start off to the Continent!  Every Englishman is noticeable on the Continent.  It would be sheer madness!”

“You think he has not gone there, then?” I cried, deeply interested.

“Of course not.  That is the point I hinted at just now.  He has defended many persons accused of murder, and he often spoke to me of their incredible folly, when trying to escape, in going by rail, or in setting out from England for Paris.  An Englishman, he used to say, is least observed in his own country.  In this case, I think I know where he has gone, how he went there.”

“Where, then?”

“Where comes last; how first.  It is a question of inference.”

“Explain.  We know your powers.”

“Well, I take it for granted that he killed her—­we must not mince matters—­about twelve o’clock; for after that hour, the servants told Lina, there was quiet in the drawing-room.  Next, I conjecture, he went upstairs to change his clothes:  he could not go forth on the world in an evening suit; and the housemaid says his black coat and trousers were lying as usual on a chair in his dressing-room—­which shows at least that he was not unduly flurried.  After that, he put on another suit, no doubt—­what suit I hope the police will not discover too soon; for I suppose you must just accept the situation that we are conspiring to defeat the ends of justice.”