The Psi Corps and President Clark, whose government has discovered Shadow vessels buried in Earth's solar system, begin to harness the vessels' advanced technology. The Clark administration continues to become increasingly xenophobic and totalitarian, and uses a military incident as an excuse to declare martial law. This triggers a war of independence on Mars, which had long had a strained political relationship with Earth. Babylon 5 also declares independence from Earth, along with several other outlying Earth Alliance colonies. In response, the Earth Alliance attempts to retake Babylon 5 by force, but with the aid of the Minbari, who have allied with the station against the growing Shadow threat, the attack is repelled.
Becoming concerned over the Shadows' growing influence amongst his people, Centauri ambassador Londo Mollari attempts to sever ties with them. Mr. Morden, the Shadows' human representative, tricks him into restoring the partnership by engineering the murder of Mollari's mistress while putting the blame on a rival Centauri House. Open warfare breaks out between the Shadows and the alliance led by Babylon 5 and the Minbari. It is learned that genetic manipulation by the Vorlons is the source of human telepathy, as it is later discovered that Shadow ships are vulnerable to telepathic attacks. Displeased at the Vorlons' lack of direct action against the Shadows, Captain John Sheridan browbeats Vorlon ambassador Kosh Naranek into launching an attack against their mutual enemy. Kosh's deeds lead to his subsequent assassination by the Shadows.
Former station commander Jeffrey Sinclair returns to Babylon 5 to enlist the aid of Captain Sheridan, Delenn, Ivanova and Marcus in stealing the Babylon 4 space station and sending it 1,000 years back in time to use it as a base of operations against the Shadows in the previous Minbari-Shadow war. Undergoing the same transformation as Delenn at the end of Season 1, Sinclair transforms into a Minbari and is subsequently revealed to be the actual Valen of Minbari legend, rather than a reincarnation. Spurred by the reappearance of his assumed-dead wife (who now works for the Shadows), Sheridan travels to Z'ha'dum, the Shadow homeworld, in an attempt by them to recruit him. However he instead destroys their largest city in a kamikaze nuclear attack, and is last seen jumping into a miles-deep pit to escape the explosion. Garibaldi, during a fight with Shadow vessels, goes missing.
克里斯·吉尔 阿雅·卡什 戴斯敏·博格斯 凯瑟·多诺休 布兰登·史密斯 Kalia Prescott 卡拉德·哈瑞斯 Johnny 5 斯蒂芬·施耐德 琳恩·A·弗里德曼 Trey Gerrald Kandis Mak 麦莉艾莉丝海顿 Jessa French Catherine Chen
达芙妮·基恩 詹姆斯·麦卡沃伊 露丝·威尔森 阿米尔·威尔森 林-曼努尔·米兰达 安德鲁·斯科特 基特·康纳 维多利亚·汉密尔顿 西蒙妮·柯比 阿德沃尔·阿吉纽依-艾格拜吉 茜安·克利福德 露塔·格德米纳斯 威尔·基恩 乔纳森·阿里斯 杰德·阿努克 寇布勒·霍尔德布鲁克-史密斯 西蒙·哈里森 金宝·张 韦德·布里格斯 杰米·沃德 布莱恩·费舍
