Olive, age 17, has a rich and vivid inner life. She has created an imaginary world that she's able to visit whenever she chooses. But her daily life on earth is shaken up by the arrival of a new roommate at boarding school, who won't leave Olive alone. And even more upsetting: a mysterious spaceman makes a surprise appearance in her imaginary world! A coming-of-age story that will take Olive far from her comfort zone, as she discovers unsuspected sides of herself and the world around her.

Olive spends much of her days in the elaborate dream world that she has created, escaping the tedium of her boarding school. It is her private space where no one can bother her. Until one day when an astronaut named Lenny appears, crashing into the water in his space capsule. Olive’s surprise deepens when she realizes that Lenny exists in real life, and a desperate search is underway to locate him following a failed reentry. With the help of her new friend Charlie, Olive will have to sift through the clues quickly in order to find Lenny and save his life. And when the girls decide to spend Christmas at Olive’s house, they find a key to the mysteries of her dream world in the most unexpected of places: right at home.

After discovering the stunning truth about Olive's past during Christmas break, Olive and her roommate Charlie are back at boarding school. Olive's link to missing astronaut Lenny Popincourt is growing stronger by the day, but he's still as far away as ever. When Lenny falls into an endless sleep, the girls formulate a rescue plan almost too risky to consider—except they're the only people on earth who can save him!

Olive is an introverted boarding school student with a very intense inner life. She has created an imaginary world she visits whenever she wants to, a world turned upside down by the arrival of Lenny, a sick and injured astronaut. She realizes that Lenny actually exists and that the capsule that brought him back from a space mission crashed somewhere on Earth – where exactly, nobody knows. With the help of her extroverted roommate, Charlie, Olive journeys deep into Siberia to save the life of this complete stranger. This is the long-awaited fourth and final installment of an unforgettable coming-of-age adventure.