Toombs and his crew rescue Riddick from the streets of Helion Prime, being chased by a Necromonger warship. They take him to the nearest prison to collect their bounty - on the fiery planet of Crematoria.
The Lord Marshal needs to see Riddick die, due to a 'Kung Fu Panda 2' style vision that a survivor from the Furian planet will destroy him. The Necromonger fleet follows the bounty hunters.
On Crematoria Riddick meets his little friend Jack - who now goes by the name of Kyra. While the bounty hunters haggle over the price, he needs to kill a few inmates and tame the odd Crematorian hound, and try to patch things up with Kyra.
The prison guards panic when they see the first signs of the Necromonger fleet. Toombs and his crew want payment, and soon there's a shootout. Toombs jumps to safety before an RPG takes out the guard tower. Riddick climbs up to the guard tower and takes the lead.
They lock Toombs in a cage, then Riddick, Kyra and a few others plan their escape -- they must track across the volcanic planet in darkness before the sun rises, and burns the surface. Meanwhile the remaining guards are running through underground tunnels to reach the bounty hunters' ship a few miles away.
The guards keep checking their progress through look-out turrets, leading to a firefight, but Riddick and his crew are still locked out. They climb a mountain as the final obstacle before they can reach the hanger, but Kyra can't keep up. Riddick tells the others to leave as the sun rises. He douses himself in water and swings down to snatch Kyra and take her to safety.
They approach the hanger as the Necromongers land. The hanger doors open and there's a nother firefight. Riddick and his crew join in, before there aren't too many left on any side.
The Commander, Vaako, shoots at Riddick - the blast catches his own man but Riddick is knocked unconscious. They take Kyra prisoner and leave the planet. Riddick is dragged to safety from the sun by an unknown hand.
When he wakes he finds his saviour was a Necromonger who is busy taking off his gear. He tells him what will happen to his friend -- and asks for his help. He wants Riddick ... as a fellow last remaining Furian, to use his ship and return to the main fleet - and take out the Lord Marshall. He hands Riddick a Furian dagger, then bravely steps out into the sun and is burnt alive.
Riddick disguises himself as a Necromonger warrior and gets inside the main ship. He alerts the Lord Marshall when one of the Necromongers who wears a mask shows up dead.
Soon he squares off against his enemy. He gets in a few good shots, and makes the old man bleed with the Furian knife, before he is beaten to the ground. Marshall tries to tear away his soul, but suddenly Riddick fights back again with more fury. Kyra comes good and lends a hand too before she is thrown against a wall, and impaled on spikes.
Vaako's wife tells her husband to seize the opportunity and join the fight, and kill the Lord Marshall. Marshall asks for his help, but instead Vaako picks up a golden axe and is about to swing it down.
Riddick is a few paces away fighting with his soul/shadow. As Vaako swings down, Lord Marshall's body jumps and lands in the soul's space ... as Riddick slams the knife point into his head.
The crowd grasp. Vaako screams in despair. Aereon (Dame Judi Dench), who floated in to watch the fight, says something along the lines of "well, that's a turn up for the books".
All the warriors fall to their knees to proclaim Riddick as their new leader.