Black Tri-Star is the twenty-fourth episode of Mobile Suit Gundam. It first aired on September 15, 1979 in Japan and on August 22, 2001 in North America.
On the moon, Kycilia Zabi reprimands her commanders and orders them to transfer some close combat mobile suits to Char, who is to be stationed with the Mad Angler squadron down on Earth. She then asks if the Black Tri-Stars have received their Doms and is told that they have. As Kycilia and her forces are occupying the Moon, they cannot join M'Quve themselves, and so she has sent the Tri-Stars as reinforcements. They descend from satellite orbit to Earth on a Zanzibar.
Back on White Base, Amuro is organizing supplies for the Gundam when Lt. Matilda stops by to greet him. Amuro offers to escort her to the bridge. They pass through different sections of the ship on their way to greet the captain and happen to pass by Kai, who is extolling Matilda's virtues to another crew member, unaware that she is there behind him. Embarrassed, Kai asks to take a photo with her, and many of the young male crew members join them. Amuro gleefully looks at his copy of the photo after bringing Matilda to Bright.
Elsewhere, General Revil is in a meeting with his men when he receives word that the Black Tri-Stars have reached M'Quve. He is well aware that this could mean trouble, as the Tri-Stars were the ones that had captured him during the Battle of Loum. Their arrival causes Revil to declare that Operation Odessa must be expedited. Elron hedges a bit, but is ultimately forced to comply. He steps outside the briefing room and tells Judoch to alert M'Quve that Operation Odessa will begin soon.
M'Quve, meanwhile, is introduced to the Black Tri-Stars and their new Doms, and is being assured by their leader, Gaia that they will succeed where Char had failed in beating the white Federation mobile suit. Night falls, and the Tri-Stars begin to search for White Base in their darkly-colored Doms, blending in almost perfectly with the darkness. White Base, which had planted sensors around the area detects them, and the crew prepares to sortie. Sayla is requested to pilot the G-Armor due to her previous experience piloting the Gundam, and Fraw Bow takes her place as communication officer on the bridge. Amuro is briefed on the G-Armor as Sayla takes her place in the cockpit. Matilda blows him a kiss before he takes off.
Outside, the Guntank is engaged in battle with one of the Doms and is having a hard time trying to hit it. On the bridge, Mirai tells Matilda that she's having trouble getting White Base to take off, as the main engine output won't rise. Sayla is also having trouble figuring out the Gundam docking procedure, but is told to launch anyway. Kai, who is stationed in the Guncannon has difficult finding the Doms in the darkness. The G-Armor launches, and while it has three times the firepower of the Gundam, maneuvering is difficult. Despite that, Amuro and Sayla still manage to land some near-hits on Gaia, who is somewhat impressed.
Up on the bridge, Mirai is informed that the G-Armor is having difficulty in battle and that the Guncannon and Guntank are falling back. Matilda volunteers to sortie in her Medea and has Fraw Bow call fellow officer Colonel Seki to tell him. Outside, meanwhile, the battle rages on. One of the Dom's shots hits the side of the G-Armor, and this prompts Amuro to undock the Gundam from it, separating the units into the Gundam and G-Fighter. Sayla is not sure that she can do it, but Amuro reassures her she can.
Amuro heads back toward White Base in the Gundam. As he goes, he sees a flaming Medea and wonders if it's Matilda's. Meanwhile, Matilda is on the bridge communicating with the engineers who are trying to get the engines to work. Just then, they are rocked by a series of blasts. The Doms have reached the ship. Mirai orders the main guns to fire their bow missiles horizontally. Amuro, for his part, is in pursuit of the Doms and gets Gaia in his sights. The two of them clash in a dogfight, although Amuro can't help but notice that the other two Doms have made it to White Base and are attacking. Matilda races out of the base to her Medea in order to launch and assist in defending it.
Gaia is beginning to realize just how formidable an opponent the Gundam is, and orders Ortega and Mash to fall into line behind him in order to perform their Jet Stream Attack. The attack catches Amuro off guard the first time, and he barely manages to evade it. However, he realizes how their trick works. Matilda's Medea comes flying up behind the Gundam, guns blazing, as the Tri-Stars prepare to make their second pass. During the attack, Amuro manages to lunge towards Mash's Dom, destroying it. Ortega Dom leaps in the air however, and with the Medea right in front of him, he smashes the bridge, killing Matilda and everyone else on board.
Gaia and Ortega retreat. Back at the Big Tray, General Revil receives the news that White Base has managed to repel the Black Tri-Stars and make it to the front, and he declares that Operation Odessa will start that day at 0600 hours, much to Elron's disappointment. As the sun comes up, White Base holds a memorial service to honor all of those killed in action in the Medea transport squadron, particularly Matilda's unit. Amuro remembers the time that Matilda blew him a kiss, and cries out her name in grief.
- Characters Introduced: Gaia, Ortega, Mash (Black Tri-Stars)
- Deceased: Matilda Ajan, Mash
- Mecha Introduced: Dom, G-Armor
- The Gundam uses the G-Fighter as the G-Armor for the first time.
- Sayla is officially made a pilot.