Five years after Kyra’s death, Riddick has become increasingly uneasy in his role as Lord Marshal of the Necromonger fleet. His refusal to swear into the Necromonger faith has caused dissent among his subjects and assassination attempts by his subordinates. After the latest attempt on his life, Riddick strikes a deal with Commander Vaako: the location of Furya and a ship to take him there, in exchange for Vaako succeeding him as the next Lord Marshal, so that he can achieve what he calls transcendence. Led by Vaako’s aide, Krone, Riddick and a group of Necromongers arrive on a desolate planet. Realizing that it is not Furya, Riddick kills most of his escort when they attempt to assassinate him. In the chaos, Krone causes a landslide and buries Riddick alive.
Riddick emerges from the rubble with a broken leg, which he sets and splints while fending off native predators: vulture-like flying animals, packs of jackal-like beasts and swarms of venomous, scorpion-like water dwelling creatures called Mud Demons. Needing time to heal, Riddick hides himself within some abandoned ruins. After he’s fully healed, Riddick notices a vast savanna beyond some rocky cliffs, but the only passage through is impeded by several muddy pools infested with Mud Demons. He begins injecting himself with Mud Demon venom in order to build an immunity and constructs improvised melee weapons, as well as raising and training an orphaned jackal-beast pup. He kills the Mud Demons and reaches the savannah. After finding a dormant mercenary station, Riddick notices a series of approaching storms, and concludes they will unleash an unidentified threat. Riddick activates an emergency beacon at the station, which broadcasts his identity to mercenary groups within the area.
Two ships promptly arrive in answer to the beacon, the first a group led by a violent and unstable man named Santana, and the second a better-equipped team of professional mercenaries led by a man named Colonel R. “Boss” Johns. Riddick leaves them a message promising they will all die unless they leave one of their ships and depart the planet on the other. Rubio, Nunez and Falco are killed by Riddick during the first night, forcing a reluctant Santana to cooperate with Johns. Riddick later steals power nodes from each of the teams’ ships and approaches Johns and Santana to strike a deal for their return. However, the conversation turns into an ambush: Johns’ second-in-command, Dahl, shoots Riddick with several rounds of horse tranquilizer, and Riddick’s jackal-beast is shot and killed by Santana.
Back at the Station, Johns interrogates Riddick about the fate of his son, William J. Johns (the mercenary from Pitch Black). When the storms reach the station, Riddick’s threat is revealed as thousands of Mud Demons emerge from hibernation underground, awakened by the rainwater, and besiege the station, killing Lockspur and Moss. Johns agrees to release Riddick in order to locate the hidden power cells. Santana attempts to kill Riddick, who is worth twice as much dead as he is alive. Riddick, with only one leg free, beheads Santana with his own machete, something he had promised to do. The group then releases Riddick.