The Indelible Past is the thirty fourth episode of Mobile Suit Gundam 00
As they flee the banquet in their Gundams, Setsuna apologizes to Tieria for slipping up; however, Tieria says he had found the distortion and swears that they will use the Gundams to destroy it. Suddenly, they are met with Ali al-Saachez, who had survived being nearly killed by Lockon four years ago, with the cost of half his body burnt. Now he wants Setsuna to pay - with his life! His Arche Gundam proves to be more deadlier; its Fangs were quicker and was able to throw away 00. Tieria goes charging in, determined to kill Lockon's nemesis and grapples Arche Gundam. Ali says that Lockon paid for going out into battle with a blind right eye; in anger, Tieria brings up a hand with a beam saber in the lower right cannon but Ali avoid it, revealing he also sabers in his legs, damaging Seravee. Setsuna returns to the fray, as does Seravee but when they are engaged at close range, Ali unleashes his Fangs, close to "blowing [them] to kingdom come" when they are luckily saved by Cherudim and Arios, who had been sent by Sumeragi. Seeing the odds are against him, Ali flees the scene. Tieria is determined to go after him but Allelujah stops him. It is then that Lyle learns about Ali.
Back at Ribbons' mansion, he chastises Regene for ruining the party; Regene counters that they could've brought Tieria over to their side if he had acted properly; Ribbons doesn't care and wants Celestial Being to continue opposing them; Healing Care says that the more aggressive Celestial Being gets, the more the public trusts the A-Laws; she asks Ribbons to let her get a mobile suit, as she is only meant for combat purposes. Regene is concerned about why Trans Am and the Twin Drive Systems were given to Celestial Being but Ribbons says it doesn't matter.
When they return to Ptolemy 2, Lockon learns all about Ali. However, he isn't concerned with revenge like Neil was; Setsuna also reveals he was with KPSA, who was responsible for the death of Lyle's family. If he had tried to stop his comrades, then Neil wouldn't have become a Gundam Meister. Though angry, Lyle says it is not good to dwell in the past, but rather fight for the future. These words have an impact on Tieria.
Sumeragi summarizes that the enemy will be surrounding them in 12 hours, so they will have to return to space where they will repair the Gundams.
Elsewhere, on a plane, Louise is reflecting on Billy Katagiri's words that Setsuna was a member of Celestial Being. Andrei, in the meantime, looks up her incident when her entire family died. He wonders if she is fighting for revenge.
Setsuna asks Tieria what distortion he had found. Just as he was about to answer, the A-Laws attack. Using Trans Am from three of the Gundams (as 00 is unable to), Ptolemy 2 is able to shoot right up into space, expanding its GN Field to maximum. It fires all gun batteries, bringing down a number of flight capable mobile suits, including Patrick's. But the Gadessa is waiting in the stratosphere, using its GN Mega Launcher to push Ptolemy off course by three degrees. Once Trans Am time limit is over, they are attack by a cruiser captained by Colonel Lee Zhejiang, prepared to destroy Ptolemy only to be caught off guard by 00, which had been launched during atmospheric exit, destroying the cruiser with two V-shaped blasts. Ptolemy 2 then receives a light message with Kati Mannequin expressed respect for Lees Kujo's tactics. Sumeragi has flashbacks and realizes there is not escape from her unerasable past.