Todesangst introduces the new sinister character Dr. Jack Newell, expert chaos theory mathematician and Director of Black Mesa R&D. Gordon Freeman and Dr. Newell have always had an adversarial relationship at best, and Gordon's hero status following the containment of Xen only served to inflame Dr. Newell's hatred and jealousy of him. The timeframe for Todesangst is set shortly after Gordon Freeman's successful return from Xen. The episode opens with a cut-scene of Mr. Blackstone (a.k.a. the G-man) arriving at Dr. Newell's office. As we soon discover, Dr. Newell has had Mr. Blackstone in his control all along, and has his own intentions for the exploitation of Xen's biological uniqueness. . . Its up to you, Gordon, to stop your evil colleague from unleashing the horror of Xen on humanity. . . if its not too late. . .