书卷一梦

　　当二战行将结束之际，核爆的阴云笼罩在广岛和长崎的上空。科技的发展对我们所处世界的安全所造成的影响是显而易见的。美国差一点就在核竞赛中失利，它也不会有如此的好运。
　　在阿尔伯特·爱因斯坦和一群值得信任的顾问的建议下，亨利·S·杜鲁门总统批准一项绝密计划，即在太平洋西北部偏远的地区设立一个住宅区，用以保护和照料全美最珍贵的人力资源。在那里居住的将是全国最伟大的思想、致力开创科学新纪元的天才科学家。在这里他们将受到最悉心的照料、获得最佳的科研环境。
　　最顶尖的建筑师和规划师们被召集到一起，来打造一个适宜这些超级天才居住的社区。这里能为他们的孩子提供最好的教育，为他们提供最好的医疗服务，在这里生活的每一个人都能这个地方能为他们的孩子提供最好的教育，最好的医疗服务，最好的生活福利设施以及生活质量。建设中的小镇堪与美国任何一个田园风光优美的小镇相媲美。他们之间只有一个区别：即这个小镇不会出现在任何地图上。至少在五角大楼也被列为“最高机密”。
　　尤利卡小镇就此诞生。但是对所有熟知小镇的人而言，这个秘密的村落决不寻常。老派而健忘的教授因为某种原因而呆在镇上；在过去五十年间，许多科学技术上的的突飞猛进都是尤利卡镇的精英研究者们取。然而不幸的是，科学的探索总是充满着坎坷，多年的试验中的履履失败，产生了无数了怪异的副产品。
　　从无私的奉献到职业妒忌，从埋头于实验至失败的沮丧，生活在小镇上人所面对的问题：是如果应对每天的挑战。但是小镇上人们具有聪颖的天赋，扭曲的心理和无限的资源，这些都成为小镇所忧虑的一大问题。人性弱点与重大科学发现在此交错，一切都从小镇开始……

　　白凌凌（周雨彤 饰）是一名单纯而又善良的大四学生，只要通过了答辩，她就将顺利的完成大学学业，步入社会成为职场新鲜人。白凌凌有一个非常喜欢的网友，名叫“永远有多远”，两人在网络上认识已经很多年了，虽然白凌凌早就对他产生了超越了友谊的感情，但她同时也明白，网络情缘不靠谱，两人相隔千里，白凌凌只敢将这份感情默默的埋藏在心底。
　　毕业答辩那天，白凌凌偶然遇见了名为杨岚航（刘以豪 饰）的男人，她的答辩因为这个男人的搅局而最后以失败告终，白凌凌不得不独自面对延毕的悲惨下场。在她最郁闷的这段时间里，恰恰也是杨岚航不离不弃的陪伴在她的身边，鼓励她跳出禁锢的思维圈子，去发掘生命更多的可能。

　　In 2261, the Vorlons join the Shadow War, but their tactics become a concern for the alliance when the Vorlons begin destroying entire planets which they deem to have been "influenced" by the Shadows. Disturbed by this turn of events, Babylon 5 recruits several other powerful and ancient races (the First Ones) to their cause, against both the Shadows and the Vorlons. Captain John Sheridan returns to the station after escaping from Z'ha'dum, but at a price: barring illness or injury, he has only 20 years left to live. He is accompanied by a mysterious alien named Lorien who claims to be the oldest sentient being in the galaxy.
　　Hours before Sheridan's return, Garibaldi is rescued and returned to the station, in rather dubious circumstances. He is markedly more paranoid and suspicious of other alien races and of Sheridan than he was before.
　　Centauri Emperor Cartagia forges a relationship with the Shadows. Londo Mollari engineers the assassination of Cartagia and repudiates his agreement with the Shadows. Londo kills Mr. Morden and destroys the Shadow vessels based on the Centauri homeworld, in an attempt to save his planet from destruction by the Vorlons. Aided by the other ancient races, and several younger ones, Sheridan lures both the Vorlons and the Shadows into an immense battle, during which the Vorlons and Shadows reveal that they have been left as guardians of the younger races, but due to philosophical differences, ended up using them as pawns in their endless wars throughout the ages. The younger races reject their continued interference, and the Vorlons and Shadows, along with the remaining First Ones, agree to depart the galaxy forever.
　　After the Shadows are defeated Garibaldi leaves his post as security chief and works on his own as a "provider of information". He begins working for one William Edgars, a Mars Tycoon, who is married to Garibaldi's former love. While he works ever closer with Edgars, he becomes increasingly aggressive towards Sheridan and eventually leaves Babylon 5.
　　Minbar is gripped by a brief civil war between the Warrior and Religious castes. Delenn secretly meets with Neroon of the Warrior caste and convinces him that neither side can be allowed to win. She tells him that she will undergo a ritual wherein she will be willing to sacrifice herself, but will stop the ritual before she actually dies. When Neroon sees that she actually intends to go through the entire ritual, he rescues her and sacrifices himself instead, declaring that, although he was born Warrior, in his heart he is Religious.
　　As part of the ongoing conflict between Earth and Babylon 5, Garibaldi eventually betrays Sheridan and arranges his capture in order to gain Edgars' trust and learn his plans. Garibaldi later learns that Edgars created a virus that is dangerous to only telepaths. It is then revealed, that Garibaldi was actually abducted by the Psi-Corps at the end of Season 3 and re-programmed by Bester to provide information to him at the right time. Bester releases Garibaldi of his programming, and allows him to remember everything he has done since being kidnapped. Edgars is killed and his wife disappears, but is reunited with Garibaldi after the end of the war. Garibaldi helps free Sheridan and return him to the campaign to free Earth. An alliance led by Babylon 5 frees Earth from totalitarian rule by President Clark in a short but bloody war. This culminates in Clark's suicide and the restoration of democratic government. Mars is granted full independence, and Sheridan agrees to resign his commission. The League of Non-Aligned Worlds is dissolved and reformed into the Interstellar Alliance, with Sheridan elected as its first President and continuing his command of the Rangers, who are to act as a galactic equivalent of United Nations peacekeepers.
　　In the season finale, the events of 100, 500, 1000, and one million years into the future are shown, depicting Babylon 5's lasting influence throughout history. Amongst the events shown are the political aftermath of the 2261 civil war, a subsequent nuclear war on Earth involving a new totalitarian government in the year AD 2762, the resulting fall of Earth into a pre-industrial society, the loss and restoration of humanity's knowledge of space travel, and the final evolution of mankind into energy beings similar to the Vorlons, after which Earth's sun goes nova.

　　《天衣无缝》改编自张勇的小说《贵婉日记》，本作也是继《一触即发》、《伪装者》后“谍战三部曲”的收官之作。故事背景和《伪装者》相同，时间线稍微提前。