Supernova follows the gripping mission of the medical vessel Nightingale 229 as it navigates the treacherous expanses of deep space in the early 22nd century. The ship's six-member crew includes its captain and seasoned pilot A.J. Marley (Robert Forster), co-pilot Nick Vanzant (James Spader), medical officer Kaela Evers (Angela Bassett), medical technician Yerzy Penalosa (Lou Diamond Phillips), search and rescue paramedic Danika Lund (Robin Tunney), and computer technician Benjamin Sotomejor (Wilson Cruz). Completing their team is Sweetie (Vanessa Marshall), the ship's on-board AI.
When they receive an urgent distress call from Titan 37—a rogue moon abandoned five years prior—the crew quickly realizes the unexpected nature of this direct communication. The signal is from Karl Larson, Kaela’s former lover, complicating the already tense dynamics onboard. Nick, an ex-military man with a troubled past, joined the crew just 12 days earlier, and his presence raises suspicions, particularly from Kaela, who is wary of him, while tensions also brew between Danika and Yerzy, who are in a relationship.
The crew's decision to respond to the call leads to catastrophe: during their dimension jump, Captain Marley sustains fatal injuries from a deadly malfunction. After this mishap, they find themselves dangerously close to Titan 37's debris cloud, resulting in the loss of 82% of their maneuvering fuel and time running out as they are pulled toward destruction by the moon's gravitational force.
As they grapple with these harrowing challenges, they discover Troy, a young man (Peter Facinelli) they rescued, who claims to be Karl’s son. This revelation is met with skepticism from the crew, particularly from Kaela, who asserts that he is not who he claims to be. Troy insists he was left stranded during a scavenging trip on Titan 37, where he discovered an alien artifact he intends to sell for profit.
Amidst the mounting tension, Nick seeks to distance the crew from the artifact, fearing its potential to cause significant danger. As emotions run high, and tempers flare, the artifact itself exhibits mysterious properties, leading Kaela to theorize that it may have been designed as a weapon against an advanced civilization. Troy's manipulations become increasingly sinister, resulting in a deadly confrontation as he reveals his true identity and the bizarre powers granted to him by the artifact.
One by one, the crew falls to Troy's relentless attacks, leaving only Kaela and Nick to face him. A fierce showdown occurs, highlighting the survivors' ingenuity as they seek to turn the artificial power against its wielder. Kaela ultimately confronts the twisted truth about her past with Karl, culminating in a thrilling climax that drives them towards salvation and the looming threat of a catastrophic supernova.
In the end, the Nightingale 229 is forced into a critical point where Nick and Kaela must share the last dimensional stabilization chamber—a decision fraught with danger, as merging their genetics could lead to unforeseen consequences. As the computer forewarns of a possible supernova scenario, they find themselves propelled back to Earth, altered by their experiences, with lingering ramifications that will shape their futures forever.
