Darrow Caldwell is an overnight polysomnographic technologist at the Somnus Alpine Institute, a highly exclusive and completely isolated sleep clinic hidden high in the Swiss Alps. Accessible only by a private cable car and catering strictly to ultra-wealthy clients suffering from severe parasomnias, the clinic is a luxurious fortress of slumber. But during a massive blizzard that severs all ties to the outside world, the fortress becomes an inescapable trap.
While monitoring the live EEG brainwaves, Darrow notices Patient 4 is in deep, Delta-wave sleep. Yet, the live security cameras show the patient getting out of bed, picking up a heavy fire extinguisher, and brutally bludgeoning the night guard to death with wide, blank eyes. Patient 4 is a "Somnambulist Assassin"-a man psychologically conditioned to execute complex, targeted murders while completely unconscious, effortlessly bypassing lie detectors and psychological screenings. Hacking the director's encrypted files, Darrow uncovers a darker motive: the clinic has been illegally mining the subconscious minds of its billionaire patients for corporate secrets, and a rival corporation has sent the sleeping assassin to wipe out the facility and erase the evidence.
Operating purely on primitive brainstem logic, the sleepwalking killer hunts strictly by tracking voluntary movement and panic responses. Cornered in the sterile pharmaceutical dispensary and unable to physically overpower the highly-trained assassin, Darrow is forced into a terrifying, desperate gamble. He spikes a water bottle on the counter with a lethal dose of liquid potassium chloride. Then, as the killer begins to batter down the reinforced door, Darrow injects himself with a fast-acting surgical paralytic. Collapsing to the cold floor, he is completely conscious but unable to move a single muscle, speak, or even blink. Forced to watch in absolute, terrifying stillness, Darrow must play dead and pray his trap works before the unthinking monster realizes he is still alive.
