A Vow of Adoration — Veronica Black

With her friends Brother Cuthbert and Detective Sergeant Alan Mill both away, Sister Joan of the Order of the Daughters of Compassion must rely on her own wits when she finds the body of a homeless man in a creepy abandoned chapel high on the Cornish Moors near her convent.

The man's identity remains a mystery, as do the activities of Michael Peter, owner of an upscale antique shop and waxwork show and husband of a woman named Crystal. When Crystal's sister comes to Sister Joan for help, the unconventional man must use all her skills to discover the truth, but before she can do so another body is found.