Plot
Twelve years after the events of Pitch Black, Riddick has become increasingly uneasy in his role as Lord Marshall of the Necromonger fleet. His refusal to swear into the Necromonger faith has caused dissent among his subjects and assassination attempts by his subordinate commanders. Riddick strikes a deal with Commander Vaako: the location of Furya and a ship to take him there, in exchange for Vaako becoming the next Lord Marshall. Led by Vaako's aide, Krone, Riddick and a group of Necromongers arrive on a desolate planet. Recognizing 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 raises and trains an orphaned jackal-beast pup. The two eventually defeat the Mud Demons and reach the savannah. Riddick notices a series of approaching storms, and concludes they will unleash countless more of the Demons, who must keep their skin wet at all times to survive. Needing to get off-world, Riddick activates an emergency beacon in an empty mercenary station, which broadcasts his identity to mercenary groups within the area.
Two ships promptly arrive in answer to the beacon, the first a group of bushwhacker bounty hunters led by a violent and unstable man named Santana, and the second a better-equipped team of professional mercenaries led by a man named Johns. Riddick leaves them a blood 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 during the first night, forcing a reluctant Santana to cooperate with Johns. Riddick later manages to steal power nodes from each of the teams' ships and then 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 Merc Station, Johns interrogates Riddick about the fate of his son, William J. Johns (the mercenary from Pitch Black). When the storms finally reach the station, large numbers of Mud Demons emerge from the muddy ground, and besiege the station, killing Lockspur and Moss. Johns agrees to release Riddick in order to locate the hidden power cells. Santana stops him and 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 sword and the group releases Riddicks chains.
They then fight their way to the ship which houses the hover bikes with Vargas being killed. Johns, Santana's man Diaz, and Riddick leave the ship together on hover bikes on a mission to retrieve the power nodes. During their journey, Diaz knocks Johns' bike over the side, causing him to crash. He is then picked up by Riddick. After they reach the power nodes, Riddick reveals to Johns about his son's addiction to morphine and a spineless attempt by his son to utilize a child as 'bait' for the hostile animals on the world they were stranded on twelve years prior. With both of them distracted, Diaz attempts to kill Riddick and Johns. Riddick fights and kills him, but not before unintentionally damaging the only working hover bike (Diaz had already disabled the other one).
Riddick and Boss Johns fend off a seemingly endless horde of Demons while running back to the station. Riddick is severely wounded. Johns takes both nodes and abandons Riddick. After treating his wound, Riddick begins to fight a futile battle against the advancing Demons. Just when it seems he is about to be killed, Johns arrives in one of the ships and shoots the creatures while Dahl descends to rescue Riddick. Riddick then takes the other ship and—as he flies away from the planet—he is stopped by Johns in the other ship. Johns asks Riddick where he will go, but thinks better and decides to not know. Riddick praises Johns for being a better man than his son and departs into deep space. In the theatrical version, this is the end of the film, while in the extended version, there is an additional scene which takes place aboard the Necromonger ship.
