Free Queens Full by Ellery Queen

When he was able to get some words out, seconds before he died, Conk Farnham and I were sure we heard him say, The heroine,’ an unmistakable accusation of you, Joan. You were heroine of the play, and Benedict didn’t know—or, as it turned out, didn’t remember—your name.
    â€œBut then the tooth-mark test proved Joan’s innocence. Dying men may accuse innocent persons falsely in mystery stories, but in life they show a deplorably simple respect for the truth. So Benedict couldn’t have meant the heroine of the play. He must have meant a word that sounded like heroine but meant something else. There’s only one word that sounds like heroine-with-an-e, and that’s heroin-without-an-e.
    â€œThe fact was,” Ellery continued, “at the very last, Benedict wasn’t answering my who-did-it question at all. His dying mind had rambled off to another element of the crime. Heroin. The narcotic.”
    He emptied his coffee cup, and Chief Newby hastily refilled it.
    â€œBut no dope was found,” Joan protested. “Where could dope have come into it?”
    â€œJust what I asked myself. To answer it called for reconstructing the situation.
    â€œWhen the act ended, Benedict entered the star dressing room for the first time. He had forgotten to bring along his make-up kit and Arch Dullman had told him to use the make-up in the dressing room. In view of Benedict’s dying statement, it was now clear that he must have opened one of the boxes, perhaps labeled make-up powder, and instead of finding powder in it he found heroin.”
    â€œBenedict’s finding of the dope just pointed to the killer,” Newby objected. “You claimed to be dead certain.”
    â€œI was. I had another line to him that tied him to the killing hand and foot,” Ellery said. “Thusly:
    â€œThe killer obviously didn’t get to the dressing room until Benedict was already there—if he’d been able to beat Benedict to the room no murder would have been necessary. He’d simply have taken the heroin and walked out.
    â€œSo now I had him standing outside the dressing room, with Benedict inside exploring the unfamiliar make-up materials, one box of which contained the heroin.
    â€œLet’s take a good look at this killer. He’s in a panic. He has to shut Benedict’s mouth about the dope before, as it were, Benedict can open it. And there’s the tool chest a step or two from the door, the tape-handled knife lying temptingly in the tray.
    â€œKiller therefore grabs knife.
    â€œNow he has the knife clutched in one hot little hand. All he has to do is open the dressing-room door with the other—”
    â€œWhich he can’t do!” Newby exclaimed.
    â€œExactly. The haft of the knife showed his teeth marks—he had held the knife in his mouth. A man with two normal hands who must grip a knife in one and open a door with the other has no need to put the knife in his mouth. Plainly, then, he didn’t have the use of both hands. One must have been incapacitated.
    â€œAnd that could mean only Mark Manson, one of whose hands was in a cast that extended to the elbow.”
    Joan made a face. “Really, Roger, was it necessary to break his wrist all over again last night?”
    â€œI didn’t like where he’d aimed that kick.” Roger grinned at her and she yanked her hand away, blushing. He promptly recaptured it.
    â€œDon’t mind these two,” Newby said. “You sure make it sound easy, Queen!”
    â€œI shouldn’t have explained,” Ellery sighed. “Well, the rest followed easily, at any rate. The night before, the hospital said they would keep Manson under observation for twenty-four hours. So he must have been discharged too late on opening night to get to the theater before the play started. He must have arrived during intermission.
    â€œWith the audience in the alleys and the fire-exit