Someone is stalking the UCLA Medical Center - a depraved madman who is preying upon the staff, particularly those who are young and female. No stranger to the terrible ravages of senseless violence, E.R. Chief Dr. David Spier must keep the emergency room running smoothly and efficiently, even as his terrified co-workers wonder who will be the next victim. But when the monster himself is dragged into the E.R. in handcuffs - hideously burned, suffering, and begging for mercy - the nightmare is far from over. It has only just begun.

The scion of an old-money San Francisco family, Daniel Brasher left his well-paying, respectable money-manager position to marry his community organizer wife and work at a job he loves, leading group counseling sessions with recently paroled violent offenders. One night he finds an envelope - one intended for someone else that was placed in his office mailbox by accident. Inside is an unsigned piece of paper, a handwritten note that says, "Admit what you've done or you will bleed for it."

Mike Wingate, abandoned by his father at four and raised in foster care, is finally living the life he always dreamed of - he's happily married with a precocious 8-year-old daughter, and his construction company is about to finish a "green" housing development that will secure a solid future for them all. But then something from his own past, a past he doesn't even remember, comes back to visit terror upon him and his family.

Over the past two decades, Nick Horrigan has built a quiet, safe life for himself, living as much under the radar as possible. But all of that shatters when, in the middle of the night, a SWAT team bursts into his apartment, grabs him and drags him to a waiting helicopter. A terrorist - someone Nick has never heard of - has seized control of a nuclear reactor, threatening to blow it up. And the only person he’ll talk to is Nick, promising to tell Nick the truth behind the events that shattered his life twenty years ago.

Evan Smoak is a man with skills, resources, and a personal mission to help those with nowhere else to turn. He’s also a man with a dangerous past. Chosen as a child, he was raised and trained as an Orphan, an off-the-books black box program designed to create the perfect deniable intelligence asset: An assassin. Evan was Orphan X - until he broke with the program and used everything he learned to disappear. But now someone is on his tail.