“The Promised World,” a psychological thriller by Lisa Tucker, explores a mysterious family history from rotating points of view. It attests to the frailty of the mind taxed by tragedy and to the power of childhood trauma and lies.

At the center of the tale are Lila and Billy Cole, unusually close fraternal twins with a shared secret. When the book opens Lila is a happily married, tenured professor who seems to have everything going her way. Then her brilliant but troubled twin brother, Billy, is shot down by a SWAT team after holing himself up with a rifle and threatening to shoot children in a nearby schoolyard.

Lila suspects her brother’s death was a suicide prompted by his depression in the wake of divorce from his wife, Ashley, and the loss of visitation rights to his children. With his death, the fragile Lila herself begins to unravel, overwhelmed with dread at the bizarre bits of their past that begin to haunt her. As she begins her emotional descent, she still worries about her promise to Billy to protect his three children.

Unable to remember any of her early childhood, Lila has been completely dependent on Billy’s interpretation of their past. She saw him as her protector. He told her she was smart and pretty and good. In his stories about their youth, he made everything turn out right – even the fact that when they were 16, the twins ran away from home to start a new life.

Lila’s husband, Patrick, who had previously asked no questions about his wife’s early years, tracks down the twins’ mother and begins to piece together a narrative. His viewpoint, along with those of Billy, Lila and Ashley, adds to the complexity of this poignant and well-written novel.