Free The Return of the Black Widowers by Isaac Asimov

and said, "Okay, I'll go out, say my good-byes, take a taxi, and have it bring me back." He was back in ten minutes.
    "Is this something about my sister, Henry?"
    "I'm afraid so, sir. I thought I had better talk to you, privately."
    "All right. Let's go back into the chamber. It's empty now."
    "Better not, sir. Anything said in that room can't be repeated outside and I do not wish to talk in confidence. I don't mind finding myself hushed up about average run-of-the-mill misdeeds, but murder is another thing altogether. There's a corner here that we can use."
    They went together to the indicated place. It was late and the restaurant was virtually empty.
    Henry said, in a low voice, "I listened to the account and I would like your permission to repeat some of it just to make sure I have it right."
    "Sure, go ahead."
    "As I understand it, on a Saturday toward the end of April, you felt uneasy and went to bed before the eleven-o'clock news."
    "Yes, just before eleven o'clock."
    "And you didn't hear the news."
    "Not even the opening headlines."
    "And that night, even though you didn't sleep, you didn't get out of bed. You didn't go to the bathroom or the kitchen."
    "No, I didn't."
    "And then you woke up at exactly the same time you always do."
    "That's right."
    "Well, now, Mr. Gonzalo, that is what disturbs me. A person who wakes up every morning at exactly the same time, thanks to some sort of biological clock inside him, wakes up at the wrong time twice a year." "What?"
    "Twice a year, sir, in this state, ordinary clocks are shifted, once when Daylight Saving Time starts, and once when it ends, but biological time doesn't change suddenly. Mr. Gonzalo, on the last Sunday in April, Daylight Saving Time starts. At one a.m. Sunday morning the clocks are shifted to two a.m. If you had listened to the eleven-o'clock news you would have been reminded to do that. But you wound your clock before eleven p.m. and you said nothing about adjusting it. Then you went to bed and never touched it during the night. When you woke at eight a.m., the clock should have said nine a.m. Am I right?"
    "Good Lord," said Gonzalo.
    "You left after the police called and you didn't come back for days. When you came back the clock was stopped, of course. You had no way of knowing that it was an hour slow when it had stopped. You set it to the correct time and never knew the difference."
    "I never thought of that, but you're perfectly right."
    "The police should have thought of that, but it's so easy these days to dismiss run-of-the-mill crimes of violence as the work of addicts. You gave your brother-in-law his alibi and they followed the line of least resistance."
    "You mean he—"
    "It's possible, sir. They fought, and he killed her at nine A.M. as the statements of the neighbors indicated. I doubt that it was premeditated. Then, in desperation, he thought of you—and rather clever of him it was. He called you and asked you what time it was. You said eight-oh-nine and he knew you hadn't altered the clock and rushed over to your place. If you had said nine-oh-nine, he would have tried to get out of town."
    "But, Henry, why should he have done it?"
    "It's hard to tell with married couples, sir. Your sister may have had too high standards. You said she disapproved of your way of life, for instance, and probably made that very plain, plain enough to cause you not to like her very well. Now she must have disapproved of her husband's way of life, as it was before she had married him. He was a drifter, you said. She made of him a respectable, hard-working employee and he may not have liked it. After he finally exploded and killed her, he became a drifter again. You think this is so out of despair; he may have nothing more than the feeling of relief."
    "Well...What do we do?"
    "I don't know, sir. It would be a hard thing to prove. Could you really remember, after three years, that you didn't adjust the clock? A cross-examining attorney would tear you apart. On the