"There was only one thing for Manning to do. He slipped into the vault and pulled the door shut. But he couldn't lock the door from the inside. He sat there, holding the murder weapon, waiting either for a chance to escape or for a chance to shoot his way out.
"Naturally, when you came aboard, the first person you looked for was Manning. You didn't see him in the casino, so you went down to the offices, found me sitting there, were in a position where you had to open the door of the inner office and pretend surprise at finding Grieb's body. You naturally wanted it to appear as a suicide, and started looking for the gun. When you couldn't find it, you realized something had gone wrong.
"It didn't take you very long to find out what that something was. Manning had been interrupted before he'd had the opportunity to plant the gun. You did some fast thinking and figured he must be hidden in the vault. You thought that Perkins or I would make a move to open that vault, so, under the pretense of trying to open it, you spun the combination so we couldn't open it. Fortunately, Perkins played into your hands by suggesting you leave it alone; otherwise you'd have pretended you'd forgotten the combination.
"You were most anxious to get rid of us, so you accused me of having taken something from the room, persuaded Perkins to take me to your cabin to be searched, turned on the signal for Manning; then, as soon as you were alone in the room, opened the vault and let Manning out. You realized at once there was one vitally weak point in your story. In order to protect yourself, no one must ever suspect you and Manning of being accomplices. So you fixed things up with Manning so he'd tell the officers he'd found you snooping around the chair in which I'd been sitting when he entered the offices. That made his story sound a lot more plausible, made it seem less likely there was collusion between you, and put you in the outer office and away from the vault door. Later on, when Manning reported that Paul Drake had employed him, you worked out a story about the target practice which would enable Manning to lay a good foundation for a suicide theory. The bullets Manning dug out from the beam were fired this morning. But, while you were doing all this, you suddenly realized there was a much better chance to pin the crime on Sylvia Oxman. So you had Manning stress the suicide angle, but were ready to toss that theory overboard if it looked as though you could pin it on Sylvia."
Duncan laughed and said, "That's one of the greatest pipe dreams I've ever heard. I always knew you were an ingenious attorney, but I never thought you'd break out with such a wild story as that in order to save a guilty client."
The Federal District Attorney nodded. "Yes, Mr. Mason, I'm afraid your desperate attempt to free Mrs. Oxman will act as a boomerang and leave you convicted of complicity in the crime by your own statements, without..."
"Wait a minute," Mason said, "I'm not talking through my hat. I have proof."
"What proof?" Duncan asked.
"Simply this," Mason said. "Belgrade was watching the entrances to the office. He didn't see Manning go in. No one saw Manning go in. No one saw Manning in the casino. When Duncan and Perkins came aboard, Manning wasn't in the casino. Manning claims that he slipped down the passageway just as Perkins and I went out, but I didn't see him and Perkins didn't see him."
"You had your backs turned to me," Manning said.
"Then why didn't Belgrade see you?" Mason asked.
Manning shrugged his shoulders and said, "Belgrade's a crook. He sold Paul Drake out. I wouldn't take his word for anything."
The Federal District Attorney frowningly inspected Belgrade. "Did you see Mr. Manning go in those offices?" he asked.
Belgrade shook his head, his puzzled expression indicating his sincerity. "No," he said. "By God, I didn't!"
The Federal District Attorney thoughtfully regarded Duncan, Manning and Mason. "This," he said irritably, "is one of the damnedest things I've ever encountered. I simply can't believe that..."
Matilda Benson interrupted him to say, "Well, I may as well confess."
"You may as well what?" the district attorney demanded.
"Confess," she said. "You don't mind if I smoke, do you, Mr. Wilson?"
"No," he said. Duncan and Manning exchanged glances, then Manning looked away hastily.
Matilda Benson calmly pulled a cigar from her leather cigar case, cut off the end, and lit the cigar before the astonished eyes of the district attorney. "This shorthand reporter is going to take down everything I say?" she asked.
"Yes. He's taking down everything," the district attorney said.
"Very well," Mrs. Benson remarked, in a voice of complete resignation. "I don't know what the punishment will be for what I've done. Whatever it is, I'm willing to take my medicine. I'm not afraid to die. My life-expectancy is short, anyway. Sylvia and her daughter mean a lot more to me than my own life. Grieb and Duncan were blackmailing Sylvia. I felt they were both a couple of rats. I didn't think they deserved to live. I went aboard the ship with the deliberate intention of killing both Grieb and Duncan."
"Were you armed?" the district attorney asked.
"Certainly I was armed," she said. "I carried a .38 automatic in my handbag. What did you think I expected to kill them with, my hands?"
"Go ahead," the district attorney said hastily.
"I watched for a chance, waiting. I saw Sylvia go into the office. I waited. I saw Frank Oxman go into the office. I opened my bag and slipped the automatic down the front of my dress. I saw Oxman come out. I saw Mason go in, and Sylvia come out. I saw Duncan and Perkins go in. Then I saw Perkins and Mr. Mason come out. I said to myself, 'Now is my time. Both the men I want to kill are in there.' I gripped my gun in my right hand and tiptoed cautiously down the corridor. I slipped silently into the outer office. I could see the door of the vault in the inner office, but I couldn't see Grieb's desk. The door blocked my line of vision; but I supposed, of course, Grieb was sitting there at his desk. I saw Duncan bending over the vault door, opening it. I leveled my gun, and was just about to pull the trigger, when Duncan opened the door of the vault and I saw Manning come out. I didn't want to kill Duncan while Manning was there, so I slipped back into the corridor. I saw Duncan come out. I followed him down to the room where Perry Mason was being searched. I listened at the door. I heard voices and learned Grieb had been killed, so I ran up on deck and waited a few moments, wondering what to do. I saw Sylvia come up, and I thought Sylvia was going to speak to me. I realized then that I'd be searched, so I tossed my gun overboard. But Sylvia didn't see me. She ran down the landing-stairs and took a launch which was leaving for the shore. I tried to protect Sylvia, because I thought she might be implicated in Grieb's murder. So I had Mr. Mason get my coat, and I threw it overboard. I smuggled Sylvia's coat ashore and..."
"You're willing to swear to this?" the district attorney interrupted, his voice excited. "You're willing to swear that you actually saw Duncan open the vault and Manning step out?"
Slowly, impressively, Matilda Benson got to her feet and held up her right hand. "You show me the grand jury room, young man," she said, her eyes snapping, "and I'll go in and swear to it right now. I'm telling the truth and nothing but the truth."
Duncan met the district attorney's accusing eyes. His own eyes were slightly squinted as though he were making a rapid mental readjustment. Suddenly he said, "They're all wet. I wasn't Manning's accomplice. I didn't know Manning was in the vault. I didn't lock it, as Mason claims. I did open it after Mason had left the office. You could have knocked me over with a feather when I opened that vault and Manning walked out. He told me he'd gone into the vault to get some papers for Grieb, when he heard someone knock at the outer door and a woman's voice call out, 'This is Sylvia Oxman. Let me in.' Grieb yelled, 'You stay in there for a few minutes, Arthur,' and slammed the door of the vault shut.