Watch Formula for a Murder for Free: How to Stream the Movie Online at 123Movies. . A fitness instructor marries a traumatized, crippled woman who suffers from PTSD and is tormented by a traumatic event that happened in her past. What is even more unfortunate is that her marriage is part of her maniac husband's evil scheme to kill her for her money. It isn't long before the formula is put into action and the gory body count starts to mount.