贝尔德上校（丽贝卡·罗梅恩饰）收到神秘信件，受邀到伦敦大都会图书馆面试，得知图书馆是守护超自然古物的古老组织，自己则被选为“守护者”，负责保护现任图书馆员弗林（诺亚·怀尔饰）。此时，反派“毒蛇兄弟会”开始猎杀图书馆员候选人。弗林与贝尔德救下三名候选人——数学天才卡桑德拉、艺术史专家斯通（克里斯蒂安·凯恩饰）和黑客伊泽基尔（约翰·金饰）。团队合力寻找“亚瑟王之冠”，但卡桑德拉被敌人蛊惑，导致弗林被亚瑟王神剑刺伤，图书馆被迫关闭。

弗林幸存后，团队转移到图书馆附馆，试图阻止毒蛇兄弟会首领杜拉克（马特·弗里沃饰）释放魔法统治世界。他们救出被囚禁的卡桑德拉，夺回神剑，但魔法已泄露导致神剑濒毁。卡桑德拉放弃用神剑治愈自己脑瘤的机会，转而救活弗林。最终弗林离开寻找重启图书馆的方法，贝尔德留下训练新人。

团队调查波士顿食品公司员工失踪案，发现其地下室藏有牛头怪迷宫。公司每7年献祭14人以换取财富。图书馆员找到控制迷宫的“线团”并关闭通道，终结献祭循环。

杜拉克绑架圣诞老人，意图夺取其魔法力量。团队救出圣诞老人并护送其前往北极，但圣诞老人中毒无法释放礼物魔力。因贝尔德是圣诞夜出生者，她成为魔力媒介，协助将礼物送往全球，化解危机。

东方龙指控西方龙窃取龙珠，要求图书馆员仲裁。调查发现实为“金苹果”作祟——持有者会变得极具攻击性。同时，杜拉克召开秘密会议，企图投票关闭图书馆。团队揭穿阴谋，保住图书馆并平息龙族争端。

一个小镇上出现了巨魔，图书馆员前往调查。接着越来越多的怪事发生，裸奔的市长，巨大的戴着粉红睡帽的狼，从狼肚子里出来的少女……原来这一切都是因为一本能够吸取人生命力并且把故事具象化的书——《上古童话》。卡珊德拉、贝尔德和斯通变成了王子公主和猎人与当地警察变成的狼战斗。而伊泽基尔则是一个盗贼，找到了为那本书提供生命力的小女孩，让她重新编写了一个新的结局，拯救了全镇的人。

图书馆员前去调查一个科学展会，这个展会上出现了一些巫术导致的异常现象。经过调查他们发现有些人使用一个据说能够提高他们能力实现他们愿望的app，这个app由复杂的咒语编写，而那些许愿的人都会受到三倍的反噬。聚集了所有的魔法力量的展会现场会变成一个巨大的能量反馈场。在这个事件背后操纵的人就是仙女摩根。图书馆员们建造了一个法拉第电笼来保护所有人，仙女摩根收集了所有的魔法力量藏了起来。

位于斯洛伐克的地脉断裂了，图书馆员前去封印，却发现地脉断裂处有一座房子，有一个小女生从那里面逃出来，说房子里有一个人抓了她的同伴，于是众人到房子里查看，却没有看到有其他人，而贝尔德看到了幻象，他们怀疑这是一间鬼屋，随机在世界各地游走。在他们继续调查的时候，一转眼伊泽基尔却消失了。墙上显示出那个小女生的名字，贝尔德便让卡珊德拉带小女生先走，结果一个黑影出现开始追杀他们，她们只好回到了房子。而斯通这时也消失了，他跟伊泽基尔待在一个缩小的模型里，在这里想要什么都可以得到。斯通看到了墙上的画才意识到不对，这时贝尔德也被传送了进来。外面的卡珊德拉意识到小女生有问题，跑进了房子，听到了房子的低语，原来这座房子其实是一个避难所，它是为了帮助所有有需要的人，能够满足每个人的愿望，但是有一天小女生一家人来了，他们是一群连环杀人犯，那个小女生跟这个房子许愿让它帮她杀人，房子感到很痛苦，于是卡珊德拉帮助它消灭了那个小女生的鬼魂，让房子解脱了。

一个UFO迷在一个小镇消失了，图书馆员前往调查。他们发现这个小镇的风格很复古，有很多煤气灯，贝尔德在碰到灯的时候消失了。伊泽基尔发现这个镇上到处都是“看不见的人”，那些人会占用其他人的身体。原来这个小镇是被尼古拉特斯拉建造，在一次实验中这座小镇的所有人被电击中，困在了维度交界处，从此不能碰到这个世界，他们想要通过这一百多年储存的电能释放出来，让消失的小镇重现。图书馆员决定帮助他们，但是在实验过程中却出现了问题，卡珊德拉决定关闭设备，最终只有贝尔德回来了，那些消失的人失去了煤气灯不能再出现了。

弗林回来了，告诉图书馆员们他找到了回去图书馆的方法。他们用之前找到的《上古童话》、线团和埃及石棺打开了大门，这时杜拉克却出现了，通过他们打开的门找到了命运的织布机，砍断了织布。历史断开了。贝尔德和弗林在平行世界穿行，分别遇见了已经是图书馆员的斯通、伊泽基尔和卡珊德拉，最后在他们的帮助下回到了自己的世界拿到了线团，穿在命运织布机上就可以重织历史。贝尔德被杜拉克刺中，生命危在旦夕，詹金斯突然出现与杜拉克打斗，弗林重织了织布，杜拉克消失了。弗林终于找回了图书馆，给贝尔德喝下拔示巴的治愈油后救活了她。最终三个图书馆员也正式毕业，可以独当一面了。

While Jenkins discovers there's something wrong with the Library since it returned from the Void, the Librarians all find themselves drawn back together after having been off on their own for months, to solve the mystery of a massive storm that has parked itself over Manhattan. They soon discover the culprit in both cases is none other than Shakespeare's Prospero.

Prospero summons other fictionals in order to retrieve parts of his staff; the librarians find themselves pitted against Frankenstein's monster and Sherlock Holmes' nemesis Moriarty; Flynn and Baird have a disagreement.

Stone, Cassandra and Ezekiel have a proper team-up for the first time in months when they investigate a cave-in at an oilrig site, which has unleashed Hokolonote, a shape-shifting god who grows in strength any time a lie is told. Now the Librarians have to come clean to each other, airing their issues and solving the riddle of the ancient prison that held Hokolonote.

Students start disappearing at Wexler College, an institution started by a mad historian/architect who believed in alternate dimensions. When the Librarians arrive, they discover a young student from the physics department is investigating the bizarre occurrences on her own. Meanwhile, Cassandra gets an offer that's difficult to turn down.

While chasing one of the Library's missing artifacts, Flynn is kidnapped by a mysterious stranger with both amnesia and a collection of all the Library's missing artifacts. Soon all of them are in pursuit of the Staff of Zarathustra before it falls into the hands of Prospero.

An old friend of Baird's is running for Mayor of a small New Hampshire town and finds himself embroiled in a scandal in the form of a missing intern and a literal contract with the Devil. Baird soon finds herself in a battle not only for her own soul, but also for the souls of all the Librarians.

When people begin suffering the effects of accidents and sins in which they have not actually been involved, the team tracks the connection to the perpetually young Dorian Gray, whose magic now works on selfies.

The Clipping Book sends the team to a high-tech research facility, where the researchers have been turned into mindless monsters by some bizarre power source in the center's lab. When they disconnect the artifact, however, they find themselves stuck in a time loop.

The team has scattered, all living the ideal versions of their lives. Soon these “strangers” are drawn together to solve a supernatural mystery – the appearance of Ariel, the sprite bound to Prospero's service. Can the Librarians do what no other human has ever been able – turn their backs on their own ultimate happy endings?

The Librarians discover that Prospero's renewed magic is wreaking havoc with the technology of the world. He is recreating an idyllic forest utopia, whether we want one or not. In order to stop him, Flynn and Baird must travel back to 1611, while the rest of the team battles Prospero in the present. Little do they realize that they can only defeat Prospero in each time by finding a way to work together – separated by five centuries.

When the Egyptian God of Chaos inhabits a human body, he attempts to release Pure Evil into the world, thus beginning the final battle of Good vs. Evil. In order to stop him, the Librarians must decipher a series of clues within a science museum, including a mysterious warning spoken by exhibit mannequins that have come to life.

Flynn leads his fellow Librarians on a mission to rescue kidnapped Charlene, unwittingly ensnaring them in a subterranean trap filled with ancient Egyptian werewolves, led by nemesis Apep, who are determined to kill the Librarians once and for all.

A routine artifact retrieval is anything but when the artifact grafts itself to Cassandra. Meanwhile a blizzard forces Stone and Cassandra to take shelter at a mysterious hotel that is hosting a demon convention, who want the artifact for themselves.

After seeing a vision of her own death at the hands of a supernatural assassin, Baird tries to cheat fate and stop the deadly prophecy from coming true.

The librarians investigate a mysterious traveling carnival where they discover the sinister secret of a magician who has been corrupted by the use of real magic.

In order to stop the spread of pure evil, the team must find the Eye of Ra and unravel the mystery of the Bermuda Triangle; Flynn must pass a series of tests.

The obnoxious Cindy Kroger has suddenly become super-popular thanks to a magical love potion. The Librarians must stop her before she launches a love missile that would force the whole world to become her fan base.

A rash of people spontaneously combusting leads the Librarians to a holistic spa run by vampires, who have discovered the secret to walking in the sun.

When the Monkey King's sacred homeland of Shangri-La is taken over by a ruthless collector of magical artifacts, the balance of the Universe is put in jeopardy, forcing all the Librarians to come together to help save the imperiled land at what could be a terrible cost.

The Librarians' two-front battle comes to a head when the Library is simultaneously infiltrated by DOSA and Apep. Flynn, Baird, Stone, Cassandra, Ezekiel and Jenkins must all put aside their differences in an attempt to save the Library, the world and themselves.

When a secret sect of the Vatican Church unearths an ancient map detailing the locations of the four cornerstones of the Library of Alexandria (the original Library), it’s up to Flynn and the Librarians – with the help of an unexpected ally – to stop them before the stones can be used to destroy the Library.

When people begin getting hurt in the unluckiest of ways, the Librarians are led to a casino where the owner appears to possess an artifact capable of stealing people's luck. Despite falling under the bad luck curse themselves, the Librarians must turn the tables before the plague of bad fortune spreads to the wider world.

When Santa takes Flynn, Baird and Jenkins on his first vacation in centuries, he leaves his beloved sleigh in the care of the Librarians. But when Ezekiel's career criminal mother steals the magic door, they must use the sleigh to save her, as well as Christmas itself, from Santa's Grinch of a brother, the Patron Saint of Thieves.

When Flynn and Baird are sucked into Baird's favorite classic Film Noir movie, the Librarians are drawn into the world of movie magic - literally - where they'll need to perfect their lassoing skills, sharpshooting, and snappy dialogue if they're going to make it out alive.

A Librarian from the past teams up with the Librarians of the present to take down an ancient and powerful enemy let loose in the modern day. When superfan Flynn is met with the prospect of teaming with his Librarian hero Darrington Dare, he could not be more excited, until Darrington leaves the Librarians with this dire warning: There can be only one Librarian - ignore at your own peril.

When Baird goes after Nicole Noone in an attempt to repair her rift with the Library, she ends up joining Nicole in a mission to retrieve a dangerous artifact before it falls into the hands of Russian grave robbers. But can she convince Nicole to forgive the Library and return home with her? Or, will Nicole open Baird's eyes to the dangers of a Guardian dedicating herself, heart and soul, to the Library?

When dissension threatens the group, Baird takes the Librarians to a charismatic self-help guru’s team building camp on the edge of a forest where people have been mysteriously disappearing. Is there a monster in the woods? Or is something more sinister going on? And can the Librarians get their team mojo back in time to defeat it?

After Cassandra freezes up during a mission, she decides it's past time to go on a vacation. Searching for her ideal town, she lands on Havenport, the "Safest Town in America." At first blush, it seems just what she needed.

When a Civil War re-enactment in a town called Feud is plagued by ghosts, the Librarians have to uncover the truth of what really happened there over 100 years ago.

When Jenkins body-switches with a 28-year-old slacker named Jeff, he must find his way back into the Library to correct the mistake. But he will need a team to do it, and enlists the help of Jeff’s hapless Dungeons & Dragons friends. Can they make it in time, before Jeff destroys the Library?

It's time to choose the singular Librarian to tether with Baird, but no one can decide so the Library takes it upon itself to help. Reducing the Librarians to their most primal selves and abandoning them in a landscape of their own nightmares, it's The Trial of the One - but can they regain their humanity in time to stop the bloodshed and prevent the death of two Librarians AND Jenkins?

After the world is morphed into a horrible and unrecognizable place – one where the Library never existed – it's up to Baird to bring the Librarians together before this bleak, knowledge-less world becomes the new reality.