I'm not sure if Kelly Reilly has a book specifically about bipolar. There could be many books out there on the topic, and without more information, it's hard to say if it's a true story.
In a horror story involving Kelly Reilly, she might be staying in an old, haunted mansion for a role. As she walked through the long, dimly lit corridors, she felt a cold breeze. Suddenly, the portraits on the walls seemed to come alive, their eyes following her every move. Every night, she heard the sound of a child crying, but when she searched, there was no one there. It was as if the very walls were haunted.
Perhaps Kelly Reilly is in a forest for a movie shoot. As she wanders off the marked path, she gets lost. The forest seems to close in on her. She starts seeing pairs of glowing eyes in the dark. Then, she hears a growl that sends shivers down her spine. Out of nowhere, a figure covered in dirt and leaves jumps at her. She has to fight for her life against this unknown and terrifying assailant.
Alvarez Kelly is a fictional tale. It doesn't draw from real events or people. The story was crafted by the filmmakers to engage and captivate the audience.