Friendship comes at a cost. For beautiful Mary-Ann Walker, who struggled with the challenges of a difficult family history, that cost proves to be her life. With Mary-Ann's past as its only guideline, the Seattle homicide unit must delve into the relationships between a misguided young woman and her family, friends, and lover. Let the psychological games begin.

Seattle Police forensic psychologist Daphne Matthews, who volunteers as a teenage runaway counselor, is haunted by the loss of a suicide, a "jumper," a year earlier. When a woman's body is found beneath the Aurora Bridge, Matthews is one of the first at the scene - and begins a puzzling investigation that becomes entangled with her own past, that of the victim, and even that of Seattle itself.

Mary-Ann's boyfriend has a record of physical abuse, and an attitude that Matthews finds difficult to crack. When the victim's grieving brother surfaces, throwing blame onto the boyfriend and craving revenge, Matthews gains an unstable ally she does not want.

Then the stalking begins: the eerie phone calls, the noises outside the house, the shadows that move in the night. Someone has his eye on Matthews - but to stop her, to kill her, or to help solve the crime?

While her colleagues Lieutenant Lou Boldt and Sergeant John LaMoia pursue a hotel room peeper in hopes of solving a series of disappearances, the police and Matthews herself are led into the "Underground" - a perfectly preserved city-under-a-city, hidden beneath present-day Seattle.

Matthews engages in a mental game of cat-and-mouse, never knowing whom she can trust. Crisscrossing Seattle, diving below the streets to ancient tunnels, running for her life, Matthews must unlock the psychological secrets behind Mary-Ann's death before she herself is buried alongside her. Matthews' very survival will depend on her skills at the art of deception.