This book belongs to a type I've seen more and more recently--a book influenced by film and/or written with an eye to film adaptation.
John Donnelly, a psychotherapist, acquires a new client, Laura. She claims to be the offspring of an alien plus a human parent (the human was abducted by aliens). Her descriptions of her upbringing among the aliens are detailed and shocking. Donnelly thinks Laura is suffering from elaborate delusions brought on by a traumatic childhood. However, he is unable to shake her delusional system. Laura claims the aliens have given her one year to make a human believe her (or something dreadful will happen). She is also trying to seduce him.
The first half of the book consists largely of descriptions of Laura's sessions and Donnelly's feelings--disturbance because he is starting to believe Laura, guilt because he is sexually attracted to her, grief over his mother's death, guilt over his long enstrangement from her.
Then madcap action erupts. It involves government conspiracies, secret agents, murders, colorful characters, love affairs, time travel, alternative time streams, religion, Hollywood, and visits to another planet with fancy scenery. And lots and lots of easy insights and meaningful emotional breakthroughs for Donnelly, his brother Hogan, and several other characters.
I said at the beginning that this book seems to be influenced by film. What I mean is the nonstop action and continual working to entertain the reader, by means of either emotional insights or humor. It doesn't seem to matter which, as long as the reader is entertained without having to think deeply. Fine if you like this sort of thing, but to me it seems rather shallow.