"For Pete's sake, Lieutenant," Macklin said, leaning a little forward and giving him no time to finish. "You've arrested the owner of that motor cruiser, and he turns out to be someone Helen Lathrup had known for five years. Not to mince words, John Darby had been her lover for that length of time, if not longer. They quarreled and she broke off with him a half-dozen times. But just recently the fire started burning again, for both of them. He practically admits all that, because I guess he knows he'd gain nothing by denying it. What he doesn't admit is that they quarreled again even more recently." Macklin paused an instant, as if to emphasize the importance of what he was about to say. Then he went on in a tone of absolute conviction: "Isn't it all pretty obvious? When the fires started burning again she sat on Gerstle's story, wouldn't let him run it. It was big, but that didn't matter. She was determined to protect Darby. Then it stands to reason they must have quarreled again. You'll never get him to admit that, because it supplies the strongest kind of motive for murder and would be the equivalent of a complete confession. They quarreled again and she threatened to give Gerstle the green light, and that's why he killed her." "A pretty drastic way of making sure," Fenton said. "Why didn't he try making up again with her?" "He probably did and got nowhere. When once her mind was made up, it usually stayed that way. Really made up, I mean. She might have quarreled with Darby off and on for years, enjoyed letting him dangle, but this time she probably turned absolutely venomous. "Consider what kind of man he is. That's important, too. A cafe society procurer--a flesh-for-sale racketeer with a capital-gains league clientele--big names in Hollywood and the TV industry, not to mention the magazine field. Consider how far that kind of upper-echelon pimp would go if she thought she was about to blow his five-million-a-year racket sky high, and himself along with it? Of course Darby killed her." "And Ruth Porges too?" Fenton asked. Macklin nodded. "She worked here, didn't she? I knew that Gerstle was working on something big which she didn't want him to publish, and she may have found out more than either Hansen or I knew or suspected. She may have found out too much for him to let her go on living. It all hangs together, doesn't it? It would be the wildest kind of coincidence if Darby just murdered Gerstle and someone else killed Helen Lathrup and Ruth Porges." "I'm afraid I can't agree," Fenton said quietly. "It would be the wildest kind of coincidence if the three crimes were not _closely related_. But they were, very closely, even if a different person committed the first two and for an entirely different reason."