Stargate: Continuum

SG-1 and Jack O'Neill attend a Tok'ra extraction ceremony for Ba'al, who asserts that he is just a clone and the real Ba'al has a secret plan. Ba'al warns of a hidden backup that could threaten their plans, setting the stage for the upcoming conflict. This introduces the central threat of Ba'al's potential escape and ongoing influence.

The authentic Ba'al uses a time machine to go back to 1939 Earth, where he massacres the crew of the Achilles, a spaceship carrying the Stargate. The captain survives long enough to destroy a crucial bomb Ba'al left, preventing the ship's destruction and altering the timeline. This event initiates a timeline where the Stargate program never occurs.

In the new altered timeline, people and objects start vanishing, including Vala Mal Doran and Teal'c. Jack is killed by a clone of Ba'al, and the remaining team members—Carter, Daniel, and Mitchell—find themselves inside the derelict Achilles in the Arctic. These disappearances signal a profound change in history due to Ba'al's time-traveling actions.

The surviving team members escape as the Achilles begins sinking. They are rescued by Colonel Jack O'Neill's team. Their escape reveals the existence of a completely different timeline, where the Stargate Program never happened, altering their past experiences and future possibilities.

The team is taken for interrogation, and although General Landry believes their story, they are forbidden from changing the timeline. They learn that in this alternate reality, Carter died in a space shuttle accident, Daniel's pyramid theories remain unshared, and Mitchell does not exist because his grandfather was the Achilles captain. They are forced into separate lives with no contact.

A year later, SG-1 is called back into action as Goa'uld scout ships appear in space. Ba'al has gained control over other System Lords and is preparing to conquer Earth. Qetesh, residing in Vala's body, becomes Ba’al’s Queen, and Teal'c is his First Prime, signaling a dangerous new threat to Earth.

SG-1 is tasked with retrieving a Zero Point Module from the Antarctic outpost by flying F-15s to the McMurdo Station. They aim to use this ancient technology to power the outpost and prepare for Ba'al's impending invasion. The mission signifies a strategic effort to restore Earth’s defenses.

Ba’al’s fleet arrives in orbit above Earth, declaring leniency towards humans. However, suspicion grows as Qetesh betrays Ba’al, kills him, and orders the destruction of key Stargate locations. The fleet begins bombarding Earth, escalating the conflict and chaos.

Qetesh reveals her treachery, kills Ba’al, and orders the fleet to destroy the Antarctic Stargate. She escapes with Ba’al’s time machine, a complex satellite-connected supercomputer to control wormhole timing, aiming to travel to the past. This act deepens the threat posed by the Goa'uld’s manipulations.

After the Antarctic Stargate is destroyed, SG-1 and Teal'c pursue Qetesh and Ba'al's forces to a Russian site where the Achilles’ Stargate was recovered. They form a truce to access Ba’al’s time machine, which monitors solar flares necessary for time travel, and plan their next move.

SG-1, faced with attack from Qetesh’s forces, dial the Stargate to 1929, ten years before their original target. Only Mitchell passes through, as Daniel and Carter are killed and Teal'c sacrifices himself to destroy Qetesh and the threat. This maneuver aims to correct the timeline.

Mitchell secretly joins the Achilles when it arrives in 1929 and kills Ba’al and his troops through the Stargate, preventing the original timeline alterations. His actions are vital for restoring the timeline and preventing Ba'al’s catastrophic plans from succeeding.

Back in the original, restored timeline, SG-1 observes the successful extraction of Ba’al, unaware of the altered history. Daniel speculates on Ba’al’s mention of the fail-safe, hinting at ongoing concerns about his secret plan. The team resumes their regular operations, with the threat of Ba’al lingering.