After the actions of Doctor Daniel Jackson and Vala Mal Doran reveal the existence of human life in the Milky Way Galaxy to the Ori, they launch a crusade to convert everyone in the Milky Way into following their religion with the intention of wiping out any who refuse. After successfully creating a black hole powered Supergate at P3Y-229, the Ori send four ships through that decimate the defending fleet in the following battle. Led by the Orici Adria, the Ori Army chooses the Free Jaffa planet of Chulak as their first target, possibly because its where the Jaffa Rebellion began. After learning of this attack, Lt. Colonel Cameron Mitchell, Colonel Samantha Carter and Captain Typhuss James Kira decide to accompany Bra'tac and his three Ha'taks to Chulak to try to stop the attack. Based on a strategy attempted by the Korolev before it was destroyed, they decide to use the ring transporter to send a bomb to the Ori ships as they fire their weapons to destroy them and hopefully save Chulak.
Emerging from hyperspace, two of the Ha'taks open fire on one of the three Ori warships in orbit of Chulak. The ship chases the two Ha'tak while the Ha'tak with Bra'tac and SG-1 on board follow. Believing that Doctor Daniel Jackson may still be alive on one of the Ori ships, Colonel Samantha Carter attempts to contact him and successfully reaches Daniel who tells her that he is on board the Ori ship that landed on Chulak. However, he quickly cuts off contact. As they chase the Ori ship, it fires and destroys one of the other two Ha'tak. Bra'tac detects the fluctuation in their shielding and moves within range as Carter informs Mitchell and Typhuss of the developments. As the Ori ship fires again, missing the second Ha'tak, Carter alerts Mitchell and Teal'c who use the ring transporter to send a Goa'uld bomb to the Ori ship. However, the bomb fails to work for an unknown reason and the Ori ship remains intact.
With the bomb having failed, Bra'tac's Ha'tak chases the Ori warship, firing upon it ineffectually. As they second Ha'tak attempts to escape, a second Ori warship swoops in and destroys it. Rather than fleeing, Bra'tac turns his Ha'tak into a suicide run upon the third Ori warship despite Mitchell and Carter's attempts to convince him otherwise with Carter believing that the impact wouldn't penetrate the ship's shields. As Bra'tac's Ha'tak closes in on the Ori ship, the USS Odyssey appears from hyperspace and contacts SG-1. Mitchell orders the Odyssey to beam the team and Bra'tac on board, revealing to a surprised Bra'tac that he had planted a locator beacon on Bra'tac earlier, just in case. The Odyssey beams the four aboard moments before Bra'tac's Ha'tak crashes into the Ori ship. The Ha'tak is destroyed in the collision, but as predicted, fails to penetrate the ship's shield and does no damage.
On the fourth Ori ship landed on Chulak, Daniel and Vala are trapped by a Prior after a failed attempt to capture Adria. Before the Prior can kill them, the Odyssey locks onto Daniel and with the Ori ship having lowered its shields when it landed, beams him out. Detecting the Asgard beam, Daniel grabs onto Vala and they are beamed to the Odyssey together. Unable to do any more and in no shape for a fight, the Odyssey retreats into hyperspace as an Ori ship fires at it, barely missing the Odyssey.
The Odyssey returns to Earth with the survivors of the battles of Chulak and P3Y-229. The Ori Army is left having successfully gotten forces into the Milky Way Galaxy with the fast-growing Orici Adria at the head to continue their holy crusade to convert the peoples of the Milky Way.