Season of Secrets by Marta Perry
As a teenager, Dinah Westlake had witnessed the murder of her pregnant cousin, but a concussion blocked her memories of that night. Now, ten years later, her cousin's widower, Marc Devlin, had returned to Charleston to give his young son a true Southern Christmas.
It was a chance to make amends in a family torn apart by the tragedy—and the suspicion that Marc was responsible for his wife's demise. But when several dangerous "accidents" occurred amid the colorful holiday celebrations, Dinah's recollections of that past dark night began to resurface. Would she discover a killer inside the man she'd grown to love?