ABOUT THREE-QUARTERS of the way into The Beekeeper (DC Books, 173 pages, $24.95 cloth, $14.95 paper), Keith Henderson`s second novel turns mean. The bulk of the book offers amusing character sketches of some eccentric `60s intellectuals as they lounge in the Ontario countryside. Then, suddenly -- strangely -- characters who trade witticisms over chess and tea begin throwing chairs and vomiting bile. It`s nervy storytelling, but ultimately it rings false. We witness this tonal transformation through the eyes of Walter Taylor, a pretentious 20-year- old who leaves his suburban Ottawa home on a trek west. He ends up staying on a bee farm with a roguish Dutch poet (the title character) and his sometime lover, Nathalie, where the three trade monologues on European philosophy and the meaning of sex. Walter`s ambivalent interest in the beekeeper`s bloated intellect becomes a violent obsession in the closing pages. The characters here are beautifully realized; Nathalie, the skittish ballerina, is especially vivid. Henderson is hilarious when he`s mocking the cerebral pretensions of the bohemian set. His descriptions, however, are turgid and overwrought, and his cruel conclusion leaves the reader wishing he had stayed fixed on his breezy course.