When Pamela Bennetts/Margaret James turned to Regency romance last year as ""Helen Ashfield,"" she delivered a solid rags-to-riches tale, Beau Barron's Lady--but it lacked the zip and chill of the best M. James gothics. Well, now this prolific entertainer has lightly, briskly packed all her talents into one bouncy little book: a Regency comedy/romance/mystery--The Philadelphia Story meets And Then There Were None--with a pinch of history to boot. Anthony, the Earl of Dunmorrow, is a dashing, handsome rake who has decided to marry (for convenience) demure, pretty Imelda Russell. Lady Davina Temple is a beautiful young powerhouse who has decided to marry pleasant, docile Sir Peter Guildford: he'll be easy to dominate. But when Anthony and Davina hear that Sir Christmas Dee is selling his splendid Ardley estate, they both show up to buy it. . . simultaneously. . . and fall in love/hate at first sight. Furthermore, dotty Sir Christmas then invites both prospective buyers (with spouses-to-be) to stay a week at Ardley before any purchase is made. Thus, there's soon a whole crowd on the Ardley guest-list: Anthony, his chum Sir Elliot Dalzell, Imelda, Davina, Davina's comely Aunt Rosamond, Sir Peter, plus beautiful Lady Jessica Barminster (with husband and lover). The host, however, promptly disappears! And a footman is found dead at the bottom of a flight of stairs. So Anthony turns sleuth--mysteriously urged on by the Prince Regent (who's staying nearby). Davina sleuths too--fearful that Anthony himself is the murderer. (She has a clue he doesn't know about.) Meanwhile, assorted romances brew: the Anthony/Davina shouting match; the inevitable pairing of demure Imelda with demure Sir Peter; the bizarre courting of Aunt Rosamond by Anthony's seemingly crazy father, who visits frequently. And finally the culprit--a murderer/traitor who's not hard to spot--traps almost everyone and is about to kill them all. . . when an unlikely hero saves the day. Funny dialogue, dandy characters (there are also some good-hearted escaped convicts lurking about), and just enough suspense to keep it all hurling along: a rare Regency treat.