Wrong Place, Wrong Time, by Gillian McAllister

A time travel story that's also a murder mystery, starting with the murder and working backward.

Jen is shocked to witness her 18-year-old son Todd murder someone who's a total stranger to her, though apparently not to him. Todd is immediately arrested, but won't say anything about it. The next day - well, the next time Jen wakes up - it's the day before the murder. Jen manages to confiscate the murder weapon before it can be used and goes to sleep, thinking she's fixed things. But when she next wakes up, it's two days before the murder...

Jen keeps going backward in time, trying to figure out why Todd committed the murder as everything she does to fix it gets erased every time she falls asleep... or does it? As time unreels itself under her feet, she scrambles to find out what was really going on with her son, and what the purpose of her travel is. Is she supposed to stop the murder? Find out why it happened? Figure out all the things she didn't know about her family? Save her dead-in-the-present father's life? Fix her relationship with Todd? Is the whole thing her fault, for being an insufficiently perfect mother? Is there any purpose at all?

This is a pretty good book that doesn't make it to excellent. It feels too long, not because there's not enough happening but because there's a lot of verbal fluff. It probably could have been cut by 20-30K words without losing any of the plot or characterization. But the conceit really is clever, and I liked her relationships with her son, a friend at work, and a scientist she drops in on periodically to quiz about time travel. There's also some nice plot twists that are unexpected but make sense - no "actually, Jen was secretly a psycho killer all along" nonsense, thank goodness.