Flicker (2016)

Noah Gale has left one case unsolved for too long and his powerful employers are not happy. Initially they plan to leave him for dead but offer him another chance, providing he investigates into the disappearance of the boss' son. Last seen at a tall, deserted, boarded up apartment block. With little choice he begins his investigation, with two enforcers keeping an eye on him. With all windows boarded up the place is a crumbling dark ruin. But as he travels through the building strange events seem to unfold. One enforcer goes missing with the other raving bout something that appears when the lights flicker on. Gale now has to travel through the entire building in the dark as the enforcer is as bound to his job as Gale is to his own. He's extremely unsettled but tries as hard as he can to believe that there's nothing there as he continues his investigation. Nothing peering out of the darkness, no extra reflections when his torch passes across the shattered glass, it's all in his head. Right?