Tristram's unflinching story manages to exist both in a vacuum and at a painfully particular point in reality. The protagonists -- a beautiful woman whose husband was killed by Muslim extremists and the married Muslim man she takes as a lover on the anniversary of her husband's death -- are nameless, the location of their one-night tryst an unidentified motel on the California coast. Yet the time is clearly post-9/11. Alternating perspectives create a balanced, taut narrative, with the language palpably unromantic: ''She tasted of aluminum and iron filings and antibacterial agents.'' While occasionally verging on melodrama, the lead-up to the violent climax achieves truly chilling suspense. But despite the emotionally candid explorations of identity, we're left with a limited understanding of how, if at all, each character is transformed by the experience.