Summary | Production | Review

SG-1 boards an abandoned Goa'uld mothership that has mysteriously arrived in Earth's orbit, and must escape the doomed vessel when it crashes into the ocean.

FAN RATING - 7.66 
NIELSEN - 1.4 
DVD DISC: Season 6, Disc 1
WRITTEN BY: Joseph Mallozzi & Paul Mullie
DIRECTED BY: Peter DeLuise
GUEST STARS: Carmen Argenziano (Jacob Carter), Colin Cunningham (Major Davis), Gary Jones (Technician), John Shaw (Dr. Friesen), Peter DeLuise (Lieutenant)
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SG-1 heads toward the planet Earth, on board a cargo ship with the Tok'ra Jacob Carter, Major Davis, and a scientist named Dr. Friesen. They're on their way to investigate a Goa'uld mothership, which has arrived in Earth's orbit – but has made no aggressive moves.

They quickly find out why: Jacob scans the ship, and finds no life signs. They board the ship, but O'Neill orders new team member Jonas Quinn to stay on the cargo ship with Teal'c. Quinn is anxious to contribute to the team and prove himself, but Teal'c reassures him that it will simply take time for the Colonel to come to trust his abilities.

On board, the team discovers that the ship is, in fact, deserted – and its self-destruct countdown is inexplicably stuck mid-way through the countdown. The engines are functional, though, and O'Neill intends to salvage the ship. Jacob, of course, urges caution. They also hear a strange static over the ship's intercom system, repeating every few minutes.

Carter and Davis investigate the computer core, and make a discovery: the ship belongs to Anubis, and is the very same ship that defeated an Asgard battleship and captured Thor ("Revelations"). Anubis implanted an advanced alien device into Thor's brain in order to download his knowledge; though the team rescued the Asgard, he has no brain activity and isn't expected to come out of his coma.

The team theorizes that when he had access to the ship's computer system, Thor may have left behind a powerful computer virus that eventually forced Anubis to abandon ship – and sent it to Earth, as a sort of gift.

Dr. Friesen asks Colonel O'Neill for a chance to look at the shield generator, as Anubis's shield technology is more advanced than anything they've ever seen. O'Neill refuses, but Friesen soon makes his way to the generator on his own. He finds three of Anubis Jaffa still on board, martial arts warriors, who kill him.

O'Neill finds Friesen's body, and warns the rest of the team – but it is too late. The Jaffa arrive on the pel'tac level and shoot Jacob with a staff weapon, then begin the ship's rapid descent into the planet's atmosphere. The Jaffa use the ring transporter to get to the cargo ship, where Teal'c (after saving Jonas's life) quickly disposes of them with a zat gun.

The fight disables the crystals that control the ship's transport rings, though, leaving the rest of the team stranded on the mothership. With insufficient time to dock the cargo ship and affect a rescue, they fall to Earth and crash into the northern Pacific Ocean.

Teal'c and Jonas return to Earth, where General Hammond gives them permission to join the rescue operation. The ship survived the crash intact, and a deep-sea rescue submarine has been dispatched.

On board the mothership, Jacob reports that his Tok'ra symbiote is healing his injuries – but he has a broken collar bone. O'Neill and Carter head back to the computer core to try and find some answers, but are trapped in a corridor when the ship seals off the area to prevent flooding. The room quickly fills with water, and Jacob tries to open the doors remotely – but he cannot. The water reaches the ceiling, and Sam and Jack have no way out.

The door suddenly opens, and water floods out, saving their lives. Jacob has no explanation.

The submarine arrives and docks with the ship, and Jonas and Teal'c board. Before they escape, Major Carter insists that they stay long enough to figure out what is going on. She has a possible explanation for the frozen self-destruct countdown, for the fact that a Goa'uld mothership mysteriously arrived in their solar system, and for the fact that her and O'Neill's lives were saved.

Thor's consciousness is still inside the computer system. He didn't leave a virus – he left himself, and has been trying to communicate with them through the static message they've been hearing. They decipher the message, and it is Thor's voice. Carter believes that if they can salvage the crystals from the computer core, the Asgard can transfer Thor into a new clone body and save him.

Jacob, Davis and Quinn are ordered off the ship, while the rest of SG-1 retrieves Thor's consciousness. But when they head back toward the sub, their only exit is blocked: another passage has been sealed as the ship continues to flood. And now that Thor is no longer in control, the self-destruct has begun again – only minutes remain.

Jack orders the others to take the sub to a safe distance, while he, Sam and Teal'c try to access the glider bay. But Sam cannot activate the force shield that will protect the bay and enable them to fly out, and the clock is ticking.

Jonas tells the others to board the sub and leave without him. He hurries down the corridor to a junction where he believes he can reroute power to Major Carter's panel; he's studied the specs on the mothership a dozen times, and knows it inside and out. He reaches the flooded compartment and swims underwater, holding his breath as he transfers the power. The plan works, and the team is able to safely access the glider bay.

Jonas swims to a nearby ring transporter, and transports himself – water and all – to another deck. He runs to the glider bay in time to join the others. The ships survive the dangerous flight through the deep sea, shooting up into the sky as the ship explodes deep beneath the surface.


  • Writer / producer Joseph Mallozzi (who co-wrote this episode, along with writing partner Paul Mullie) called this episode "a BIGGIE" that will have long-term consequences.
  • Actor Colin Cunningham ("Major Davis") reported via his official Web site that "Descent" originally included a scientist named Nolan. But he suggested to DeLuise that it would be a good role for Major Davis, and convinced executive producer Brad Wright that he should have the part. "First actor I know that has ever suggested himself ... and turned out to be right," Wright said.

    Cunningham also said that Major Davis' role isn't too large in this particular episode. "I've only the occasional 'Colonel, look!' kind of dialogue," he said. "And so, I'm thinking ... What if I play these scenes like I've got a big crush on Major Carter? Just the odd look from time to time." (He added, however, that the idea was nixed.)" (Colin Cunningham, via
  • "Peter DeLuise directs episode three, 'Descent,' written by myself and Paul Mullie. This one will be another terrific-looking episode in which we do something we've never done before. We actually sunk a set for some very cool underwater sequences. Yup, our cast gets good and wet. The sequences look truly amazing. Special guest star, as most of you know, our man Major Davis." (Writer / producer Joseph Mallozzi, in an online chat at SG1 Fans)
  • "They're called Ninja Jaffa because they're an elite cadre of Jaffa. You caught a glimpse of them if you watched 'Revelations.' They turned out great. Slice and dice." (Writer / supervising producer Joseph Mallozzi, in an online chat at GateWorld Forums)
  • "In Season Six's 'Descent,' [director] Peter DeLuise has a small part as a member of the submarine personnel dispatched to assist in the rescue. His name tag reads: 'Lt. Dagwood,' the character he played in Seaquest." (Writer / supervising producer Joseph Mallozzi, in a post at
  • "One sequence had Carter and O'Neill trapped in a chamber that was slowly filling with water. We achieved this by actually doing the opposite. We lowered the specially designed set into a pool, giving the impression that the water was actually rising. We shot at Vancouver's Olympic pool and it was a tough day. Rick and Amanda were very wet and very cold, and had to sport wet suits underneath their clothing to keep warm.

    "This episode also marked yet another cameo by Director Peter DeLuise, this time offering a tip of the hat to his old show, Seaquest, by playing the part of 'Lieutenant Dagwood.'" (Writer / producer Joseph Mallozzi, in a post at his blog)