This episode began with Marina Ismail saved by Setsuna F Seiei and was part of the crew when they are going to meet the local faction, Kataron. A faction against the Eart Federation and in particularly, the A-Laws.
A-Laws found the location of Celestial Being mothership in deep sea and had despatched a new water-typed GN driven Mobile Suit to attack it. The technology was surprising as the weapon are able to break the GN forcefield of the Celestial Being mothership. Setsuna with his Gundam 00 together with Allelujah, Tiera and Lockon managed to pulled through.
Marina Ismail, Princess of Azadistan met with her former assistant Shirin and she was incidentally part of Kataron.
For the video streaming of Gundam 00 Season 2, Episode 4, visit this review page for direct link.