His Only Son recounts one of the most controversial moments in the Old Testament—when Abraham was commanded by God to sacrifice his son Isaac on the mountain of Moriah. While traveling to the place of the sacrifice, alongside Isaac and two servants, Abraham is flooded with vivid memories from the years he and Sarah spent longing for the son they were promised—the son he must now lay upon the altar.

Having survived a brutal home invasion that left his fiancee dead, Scott, now emotionally unstable and reclusive is encouraged to join a support group in an attempt to get his life back on track. At the group he meets the enigmatic O, a woman who claims to have ties to Scott's attacker. Together the two set on a path of vengeance to track down the monster who did them wrong but as their journey progresses Scott begins to question O's true motives and intentions as she pulls him deeper into a world of murder and lies.