Caterina Cammino is a lonely, attractive, and stylish thirty-five-year-old woman whose nightly ritual is to go to the beach and drink wine from the bar of her car while watching the sunset. She has never come to terms with a devastating event that happened in 1988: When she was seventeen, she and her best friend Tracy, both in Italy for summer school, had been invited to a party. The girls were drugged, raped and discarded outside by a swimming pool. When Tracy got up to wash off in the water, she drowned accidentally, and Caterina has never forgiven herself for her friend's death. Though time has continued, in her life, relationships and emotional maturity, she is still a seventeen-year-old girl, stuck in that night when she lost her innocence and awoke to a scream.

Tyler Beck is an eighteen-year-old loner who was born to a drug-addicted mother and an emotionally distant father. He is gifted intellectually and has an awareness of a special magic that includes visions, phantasms, and a cord above his right shoulder that other people do not perceive. When his mother dies, the magic disappears, and at age fifteen he decides to kill himself with a heroin overdose. He is rehabilitated with the help of a counselor named Robie, who becomes his first and only friend. After Robie dies in Iraq, however, Beck leaves Robie's funeral, takes another shot of heroin down at the beach, and passes out in the sand.

Their lives collide when Caterina's car accidentally strikes a trashcan that crashes into the semi-conscious Beck. When they both ask aloud for help, the grieving parts of themselves are transported to another dimension called 10-17. Caterina arrives in this dimension as her seventeen-year-old self, Cat, and there she meets Beck, still wearing his pallbearer's suit, whom she nicknames Ty. Once in this new world, set against a backdrop of Italy, they meet a Watcher-Numen named Miranda who tells them that they are in this time-space classroom for learning and healing, even while their lives are continuing and intersecting on Earth, also known as Dimension 10-71. Miranda explains that these dimensions are like a window blind, with the segments of 10-17 and 10-71 being adjacent to each other and nearly touching. Miranda informs Cat and Ty that there are many slats on the blind, including one called Dimension 2-26, an existence much like life on Earth, but without suffering or addiction, and which is populated by humans of a higher vibration. She mentions in passing that it is a place called Thare.

To the eighteen-year-old Ty, the seventeen-year-old Cat from 1988 is a technological alien. Beck is attracted to the mature Caterina, even though he views her as an eccentric woman who relates to life through song lyrics, and who lives in a music-infused, alcohol-soaked silo. After shaky starts in both dimensions, they begin to heal each other and recycle their pain into something positive. While Beck, who has lived in his own solipsistic world for most of his life, readily embraces his love for Caterina, she is conflicted over her feelings for a man half her age. Meanwhile, in Dimension 10-17, as Cat and Ty complete their lesson, they are torn over the choice that Miranda offers to them: To go to the "perfect" world of 2-26 at whatever adult age they wish to be, and leave the Earth and their families behind, or to return wholly to their Earthly, 10-71 selves...