With no history, and few atmospherics, MacLeod (King Stork, We Dare Not Go A-Hunting) has contrived a mystery much closer to her adult whodunits--with vicarious satisfactions aplenty for adolescent females and, alas, a dead-head resolution. Jenny Cirak, 19, has just inherited a fortune and a cottage in tiny Meldrum, R.I., from the father she never knew: one-time celebrated, long-obscure filmmaker Jason Cirak, known in Meldrum as James Cox. Happily leaving her self-pitying mother and patronizing relatives, Jenny takes over the cottage--and, of course, sets out to find out what-was-what with her father . . . who, it immediately transpires, died too-mysteriously on his back doorstep. But the making of the book, and the saving of Jenny, is elegant, quick-witted, middle-aged Baltimore C.P.A. Harriet Compton, who arrives on a purported ""wild goose chase,"" settles in as Jenny's ""aunt,"" helps her sort out the local suspects, and turns out to have a very personal interest in the case. A red-herring culprit and a real culprit who are psychos are the one disappointment. Otherwise: a sparkler--entertainingly peopled and deftly written.