The Darkest Evening of the Year by Dean Koontz

The darkest evening of their lives is approaching...

Amy Redwing runs a dog rescue charity, not something for the fainthearted. She's lucky to have a friend, Brian, who'll ride shotgun with her. Nervously. He knows there are no limits to what Amy is willing to risk, even if the abused dog is owned by a violent drunk.

Brian always blamed Amy's work for her refusal to marry him. Now he has become aware that someone is watching Amy's every move - and he begins to suspect that a shattering secret is hidden in her past.

He's the one man who might save her, but he has a problem of his own in the terrifying shape of Vanessa, his ex-lover. She comes crashing back into his life just as Amy needs him most...