It's been five years since Riddick (VIN DIESEL), a convicted murderer, survived both crash landing on a remote planet and the repeated attacks of carnivorous monsters there. Now the only thing he runs from are bounty hunters such as Toombs (NICK CHINLUND) who try to capture him for a handsome reward. Riddick overpowers Tombs and his crew and takes their ship, returning to a planet where he hopes to find the only two people he rescued from that nightmare.
He comes across Muslim cleric Imam (KEITH DAVID) and learns that the other survivor, a young girl named "Jack," is now in prison. As informed by the mysterious ambassador Aereon (JUDI DENCH), however, he and the rest of humanity have bigger things to worry about.
It seems that a super race of beings known as the Necromongers are taking over the universe, killing off or enslaving nearly everyone. Led by Lord Marshal (COLM FEORE) and his right-hand man Vaako (KARL URBAN), the Necromongers are out to conquer this planet, and Aereon wants to hire Riddick to deal with the invaders.
He wants nothing to do with this battle and thus sets off for another planet where a subterranean prison holds Jack who now goes by the name of Kyra (ALEXA DAVALOS). As the power hungry Dame Vaako (THANDIE NEWTON) wants her husband to usurp Lord Marshal's command, Riddick must not only deal with both Vaako and Tombs being after him, but also the penal planet where the rising sun sends temperatures soaring and burns up anything in its path.