Pendulum(2015)

When Luther, the CEO of a major software company, realises he has a stalker intent on doing him harm, he calls in Ryan, an old friend and former soldier. Ryan, who is battling with post-traumatic stress disorder, tracks down the stalker and is forced to kill him, but in so doing, makes a shocking discovery. Now Ryan must decipher whether he is being framed or succumbing to the delusions of his illness.