''She understands Karma, she says: "What I do, I reap"''Her name means sadness, yet Tristessa, a prostitute and morphine addict, lives without cares in her shabby room with a menagerie of pets and an altar to the Virgin Mary. Based on Jack Kerouac''s own real-life love affair in Mexico city, this is the story of a man''s ill-fated relationship with a woman he portrays with tenderness and dignity, even as her life spirals out of control. ''A narrative meditation studying a hen, a rooster, a dove, a cat, a chihuaha dog, family meat, and a ravishing, ravished junky lady, first in their crowded bedroom, then out to drunken streets, taco stands, and pads at dawn in Mexico City slums'' Allen Ginsberg