Before birth Reva was exposed to a bizarre alien force that changed her genetic makeup and gave her the unique ability to see different lines of causality spread out before her. When she chooses any one of them, the other possibilities fade into nothingness and the new reality becomes her "Mainline." She uses this special talent as an assassin for hire - slipping in and out of realities, she strikes and then disappears. She is unstoppable and uncatchable.
But don't tell that to bodyguard Yavobo, an eight-foot-tall member of a warlike alien species whose hormone-induced rages make them walking machines of destruction. When Reva takes out his boss, he swears a blood oath to track down and kill the assassin.
Yavobo has set himself no easy task. Danger is Reva's game, and no one had beaten her at it yet. But when she meets a young smuggler who reminds her too much of herself, a little helpful advice soon turns into much more than that. Suddenly she is faced with the powerful urge to give up her life roaming the lines and stay forever in one "Mainline." But while friendship may dispel the demons that have haunted her since childhood, it may also prove her undoing - she may no longer be able to escape the deadly hunter on her trail.