In 3028, humanity has mastered deep space travel and interacted with several alien species. A human invention called “Project Titan” alarms the Drej, a pure energy-based alien species. As the Drej start to attack Earth, Professor Sam Tucker, the lead researcher for “Project Titan”, sends his son Cale on one of the evacuation ships with his alien friend Tek while Tucker and other members of his team fly the Titan spacecraft into hyperspace. The Drej mother ship arrives and fires a directed-energy weapon into the planet that completely destroys Earth, while debris from the explosion also destroys the Moon. The surviving humans become nomads, generally ridiculed by other alien species.
Fifteen years later, Cale works at the salvage yard in an asteroid belt called Tau 14. He is tracked down by Joseph Korso, captain of the spaceship Valkyrie. Korso reveals that Tucker encoded a map to the Titan in the ring he gave Cale. Tek tells Cale that humanity depends on finding the Titan. When the Drej attack the salvage yard, Cale escapes aboard the Valkyrie with Korso and his crew: Akima, a human female pilot, along with Preed, Gune, and Stith, aliens of various species.
On the planet Sesharrim, the Gaoul interpret the map, and discover the Titan hidden in the Andali Nebula. Drej fighters arrive, capturing Cale and Akima. The Drej eventually discard Akima and extract the Titan’s map from Cale. Korso’s crew rescues Akima, while Cale eventually escapes in a Drej ship, and rejoins the group. Cale’s map has changed and now shows the Titan’s final location.
While resupplying at a human space station called New Bangkok, Cale and Akima discover that Korso and Preed are planning to betray the Titan to the Drej. Cale and Akima manage to escape the Valkyrie, but they are stranded on New Bangkok when Korso and the rest of the crew set off for the Titan. With the help of New Bangkok’s colonists, Cale and Akima salvage a small spaceship named Phoenix and race to find the Titan before Korso does.
Cale and Akima navigate through the ice field in the Andali Nebula and dock with the Titan before the Valkyrie arrives. They discover DNA samples of Earth animals, and a pre-recorded holographic message left by Professor Tucker who explains that the Titan was designed to create an Earth-like planet. However, due to its escape from Earth before its destruction, its power cells lack the energy necessary for the process. The message is interrupted by the arrival of Korso and Preed. Preed reveals himself to be a mercenary for the Drej and betrays Korso while holding him, Cale, and Akima at gunpoint. Preed attempts to kill all three of them for the Drej, but he is killed by Korso. He and Cale then fight until Korso falls into the depths of the ship.
Moments later, the Drej attack the Titan. Given the fact that Drej are, essentially, beings of pure energy, Cale realizes that modifying the Titan to absorb them will re-energize the ship. In order to put this plan into effect, Cale must repair significant parts of the ship; he sets off to do this while the remaining crew of the Valkyrie distract the aliens. Korso, who survived and overheard Cale’s plan, shows up and helps stall the Drej and then sacrifices himself to complete the repairs. The Titan absorbs the Drej mothership along with everything aboard, and uses this gained power, along with the ice field, to generate a new, habitable planet.
Cale and Akima stand in the rain, gazing at the beauty of their new home and discuss what this planet should be called. Stith and Gune do a fly-by on the Valkyrie as colony ships, filled with humans anxious to start life anew, approach.