IN Deadly Reunion (Gynergy/ Ragweed, 190 pages, $10.95 paper), her second mystery featuring the lesbian sleuth Harriet Hubbley, Jackie Manthorne not only demonstrates that she is prolific (the first in the series was published in 1994 and a third is forthcoming) but also nudges her unconventional heroine gently towards the mainstream. Harriet's return to Spruce Bay, Nova Scotia, for her high-school reunion is complicated by her reluctance to reveal her sexual orientation in her home town -- and by her annoyance at the prospect of concealing it. Still (as in her first adventure, Ghost Motel) agonizing over her lover Judy's desire for an "open" relationship, she herself quickly -- and quite explicitly, family-valuers be warned -succumbs to the charms of a former classmate she once admired from the closet. As she uncovers a morass of sexual entanglements leading to a killer, she also learns that almost everyone has known her ,.secret" all along.

A detective becoming involved with a possibly duplicitous suspect is a venerable tradition (think of Sam Spade and Brigid O'Shaughnessy, for starters), but Judy and Harriet's Harlequinesque tribulations, and Manthorne's didactic tendencies, slow the plot down. However, the issue of fidelity resonates in the denouement of Deadly Reunion, which turns out to be something of a cautionary tale about the risks of careless dalliance.