Sheridan is believed dead in the first episode, though he returns in the second, seemingly back from the dead. He has met "The First One" on the planet of the Shadows and this wizened creature, who looks like a wizard, restored his life energy. However, he's only able to give Sheridan another twenty years of life.Sheridan and Delenn begin a relationship and it's revealed that Delenn is a child of Valen. Valen was the human who transformed into a Minbari and went back in time 1000 years to win their war against the Shadows. Girabaldi reappears after being missing for two weeks and his attitude it much darker, which has something to do with where he's been. It turns out his mind was messed with by Becker, the evil Psi-cop. He eventually becomes free of Becker's control but it takes its toll on him. Girabaldi reunites with is ex-girflriend, who is now married to the richest industrialist on Mars. Unfortunately, this guy is on the side of the corrupt President Clark, who is in league with the Shadows. In fact, earth is making new ships from the Shadow technology.
Marcus Cole (Jason Carter), a Ranger, falls in love with commander Susan Ivanova (Claudia Christian), though it's never really reciprocated. By the end of the season he makes a huge sacrifice for her, when she's mortally wounded. Sheridan also puts together the White Star Fleet, a hundred ships that combine Minbari and Vorlon technology to fight the shadows. Meanwhile, Londo has to deal with the new evil emperor of the Centauri, who is also in league with the Shadows.
This is really the season where everything happens and there's a final confrontation between Sheridan and the Earth fleet. And the Inter Stellar Alliance is formed. The last episode of the season is very cool, as it takes place in the distant future and shows key moments in history. Thousands of years in the future Earth goes through another Dark Age and in the end humanity becomes a form of pure energy, like the Vorlons. If the series had ended with Season Four, this would have been an entirely satisfying conclusion.