Bestselling British author Barclay (A Lovely Illusion) delivers another enjoyable, fast-paced crime novel, her second (after 2002's Farewell Performance) to feature former Crown Prince Gregory of Hirtenstein, now working as a concert arranger (and sometime detective) under the name of Gregory Crowne. When Crowne and his girlfriend are invited to a private Greek island for a birthday party for a rich heiress, they are unsettled by the woman's flashbacks to time spent at a snake laboratory. Their hackles are only raised further when the heiress's husband, a private doctor, and a nurse, who seems more like a warder than a caregiver, attempt to persuade them that everything is normal. Although the mystery is more a what-was-done than a whodunit, it is a pleasant, old-fashioned puzzle with attractive contemporary trappings. (Mar.)