"He had a latch-key, which he had procured from Walter. I daresay he intended to kill Walter--either shoot him or stab him--and then go away, leaving Frank to bear the blame. He went to Frank's chambers to prove an _alibi_. But when he found Darrel in the room he saw that the deed was done. To make himself safe he made Darrel sign a confession, and kept it in his strong-box. Then the two agreed that Frank should bear the blame. Now you can see, Mildred, why Darrel was unwilling to denounce Frank when he recognised him here. He feared to be implicated in the case. But his rage got the better of him, and he took Berry and Fan to the secret rooms of Balkis."
"What has become of Balkis?"
"She has disappeared; no one knows where. I expect she had made all arrangements and has departed for the States. It's just as well, as she is wanted for the murder of those three."
"Why did she murder them? I thought she was friendly with them."
"She was in a way. But she was madly in love with your brother, and was under the impression that he would marry her. He might have done so, for Balkis is rich. However, if he got Lancaster's money he intended to marry Fairy Fan. When, by means of that letter, I proved that Fan had been making love to Starth, Balkis was furious. Then, when she found that Darrel had killed her lover, she determined on his death."
"Had Frank killed Walter, would Balkis have--"
"I am sure she would," interrupted Eustace, quickly. "She was a most furious woman, and would have stuck at nothing. And she didn't. She resolved also on the death of Berry, because he had caused all the trouble, and had really brought about the death of your brother by his machinations. So she closed them in the room and let the river in. The three poor wretches were drowned like rats in a trap before I could get back with the police."
Mildred shuddered with horror. "Had she designed all this?"
"No. To do her justice I don't think she did. The trap was arranged for the police should they have made a raid on the gambling-rooms. It seems that the inner room was only divided from the river by a thick wall. There was a tunnel through this, closed at the lower end by an iron slide, which was worked by a lever from the outer room. Balkis shut the three in, and Darrel was fighting with the Captain. Then when she got rid of us--I went to fetch the police, remember, as I suspected foul play--she must have worked the lever and admitted the water. Great Heavens!" said Eustace, covering his face. "I can imagine the feelings of those poor wretches when they saw the water pouring into the room. Bad as they were their punishment has been terrible."
"Were they all three dead?"