Both cliffhangers and "interior" stream-of-consciousness novels can tell a story that spans an hour or a day. Cynthia Thayer has combined both in A Brief Lunacy, a 24-hour look at a day like no other in the life of Jessie and Carl Jensen.

Carl, a retired orthopedic surgeon, and Jessie, a retired teacher, live amiably enough in rural Maine, painting still lifes, knitting, house mending, and pondering the lives of their grown children and the seagulls outside. He is loving, competent, and commonsensical but harbors a traumatic past in Nazi Germany, which he never discusses. She is also loving, is a ruminator, and leans on Carl as "Mr. Fix-it." Neither love nor a handyman, however, has been able to "fix" their mentally ill daughter, Sylvie, who is alternately childishly loving and spouting venomous rage.

In an unexpected phone message, Sylvie announces she is leaving the family home and hitchhiking to South Dakota for no apparent reason. "And guess what," she adds, "there's a guy here in the loony bin who loves me." Through flashbacks and interior monologues, we learn of the devastating impact of Sylvie's gradual slide into schizophrenia and the source of her parents' immediate angst over her runaway.

Time slows to a crawl, barely disturbed by a nosy neighbor and finally punctuated by a knock on the door. Enter a handsome young man who will bring about irrevocable and terrifying changes over the next 20 hours. The identity of this individual, "Jonah," and the effect of the self-declared "mission" he imposes on Carl and Jessie drive them through a life-changing transformation. The two discover barely imagined facets of themselves, deeper truths about Carl's ordeal in Nazi Germany, the strength of Jessie's character, and the power of self-deception.

Thayer does a remarkable job of interweaving plot and character development and gives a credible portrayal of mental illness, traumatic stress, the uncertainty of our inner world, and the puzzle of motives that drive our choices and therefore our lives. And she keeps us close to the edges of our chairs as the ordeal unfolds up to the denouement. Her characters are both internally consistent and able to develop and evolve through the crucible of their torment. The extraneous is melted away, and the truths at the core are exposed.

Although the book is dedicated to "the memory of the thousands of Roma, taken in the night from the Gypsy camp at Auschwitz-Birkenau," it is equally an homage to the tyranny of mental illness. Anyone whose life has been touched by mental illness, as well as readers who just fancy a good psychological thriller, will find ample sustenance on which to chew.

Dr. Backlund is a psychiatrist at Compass Health and is in private practice in Mount Vernon, Washington.