Blood pact - Tanya Huff

It began, as it so often did, with a body. Only this time death has struck close to home for Vicki Nelson, PI. Her mother is the victim. And what at first seems no more than a tragic natural death is about to become the most terrifying case of her career.

For Vicki and her sometime lover, the vampire Henry Fitzroy, have discovered something suspicious in her mother's demise. Vicki feels unable to deal with the grief until she's investigated what happened. But she soon discovers that it's not just memories that can be difficult to lay to rest.