Seven disparate individuals first meet by chance in the sleepy town of Trostenwald, but they quickly become involved in an investigation after a zombie attacks the recently arrived traveling carnival. Out of necessity, they come together as a group, calling themselves the Mighty Nein and setting off north. In the aftermath of the attack on the Zauber Spire, they find themselves exploring the underbelly of Zadash, gambling their fates with the Gentleman, and riding across the swamps of Berleben before engaging in merriment and mayhem among the folks of Hupperdook, oblivious to their soon-to-be changing fortunes.

The Mighty Nein scramble to recover those who were lost, and the attempt bears a heavy cost and an unexpected gain. Then, in pursuit of clues as to Fjord's mysterious patron, the party arrives in Nicodranas, the home of Jester. But their respite is short-lived as their adventure sets sail to the seas, where both answers and dangers lurk from above and beneath.

The Mighty Nein return to the mainland and travel deep into Xhorhas in search of the missing Yeza. Upon finding an "anchor" to the Abyss, the party earns the favor of the Bright Queen Leylas Kryn. From their new home base in the capital of Rosohna, they continue their search for answers and in the course of their chase, they end up losing one of their own to Obann, a servant of the Chained Oblivion.

The Mighty Nein seeks to free Yasha from Obann's control while Fjord struggles to free himself from Uk'otoa's. Meanwhile, the Angel of Irons cult has their own plans to release their god. Complicating things further, the party finds themselves drawn deeper into the tangled webs of intrigue between the Dwendalian Empire and the Kryn Dynasty with the fates of both territories hanging in the balance. Crit Recap Animated calls this sequence of episodes "The Sword & The Angel".

With a tentative cease-fire in place, the Mighty Nein make time within their hectic schedules to plan for Traveler Con and to catch up with their own separated families and former friends. Soon after peace is apparently made a reality, the party finally arrives at the long-awaited destination of Rumblecusp for the event that Jester and the Traveler spent half a year preparing for. However, they discover more secrets, oddities, and threats than expected, including the potential loss of their own memories and selves and an even more chilling omen on the horizon.

The Mighty Nein pursue a familiar face north to Eiselcross toward the ruins of the ancient magocracy of Aeor. The cold circumstances lead to even colder complications, however, with knowledge of an encroaching threat from the distant past threatening to return: the Somnovem. Armed with this knowledge, the Mighty Nein consolidate their alliances and goals, travel across the land and even the planes, and engage in a desperate race against time that will determine the fate of their home and those they hold dear.

After their original adventures together in Campaign Two of Critical Role, the tale of the Mighty Nein wasn't over yet.