The special picks up directly after the Metalocalypse season 4 finale. The special begins with Ishnifus Meaddle chanting and singing with the monks of the Church of the Black Klok about the Doomstar being born, and that before the "prophet's night" is over, one of them must die. It then cuts to Magnus Hammersmith and the Metal Masked Assassin holding Toki Wartooth and Abigail Remeltindrinc prisoner, keeping them both just barely alive in order to lure the remaining members of Dethklok into their trap. Meanwhile, Dethklok is "partying around the world" in an attempt to forget that Toki is missing, while Charles Offdensen is in the control room attempting to locate Toki. The Klokateers' best operative has returned dead, with a USB flash drive found in his remains. It contains a video of Magnus holding Toki and Abigail hostage, saying that his location is at the "depths of humanity".
Ishnifus tries to motivate Dethklok to search for Toki, calling them "brothers", but Dethklok denies that they care about Toki. Dethklok then collectively laments about the weight that is being put on their shoulders, and question their ability to rescue Toki if it comes down to that. Ultimately, they refuse Ishnifus's plea. At a live show, the band uses a hologram to represent Toki, but it malfunctions, and the fans begin booing Dethklok. Realizing that they have no other choice, Dethklok finally makes the decision to find and rescue Toki.
Abigail comforts Toki in an attempt to ease his fears, urging him to go to his "happy place". This is shown to be the day when Toki first auditioned to be in Dethklok. The band needed a new guitarist after they kicked out Magnus, so Skwisgaar Skwigelf engages in a guitar battle with the hopeful tryouts, defeating them all. Toki arrives late, but Skwisgaar gives him a chance anyway. They begin a guitar duel, in which Toki is able to perform nearly on-par with Skwisgaar. Eventually Toki makes a mistake at the end of the duel, and while the band says he can't join, Skwisgaar says, "Nobodys ever made me play so well", and invites Toki to join Dethklok. Toki then thinks of his happiness at the band's subsequent fame and fortune, and at his acceptance in the band.
A meeting of the Tribunal is shown, with Mr. Salacia, Senator Stampingston, General Crozier and Vater Orlaag present. They mention Dethklok's decision to rescue Toki, and discuss that they have a traitor within Dethklok's ranks. Meanwhile, Edgar Jomfru helps the band prepare for their rescue mission, and both he and Ishnifus have some inspiring words for them. Before they leave, Offdensen resigns as their manager, saying he can no longer protect them.
Dethklok realizes that "Depths of Humanity" is the name of the club where Toki played his first gig with Dethklok, and goes there to find him. Instead they encounter their old band manager, Skwisgaar's old guitar teacher, and old groupies. They harass Dethklok about how the band abandoned them. One member pulls Murderface aside to greet him and "accidentally" cuts Murderface's wrist, appearing to implant something in Murderface. The rest of the band grab Murderface and flee the club. Skwisgaar shows the band an old flyer for the rehearsal space where they auditioned Toki, and they head there to find him.
On their way they encounter a mob of zombie-like musicians and drug addicts. With some help from Dr. Rockzo and their own checkbooks, they get past and head into the rehearsal space. They are ambushed inside by the Metal Masked Assassin. However, Ishnifus appears and sacrifices him self as a distraction, so that Dethklok can proceed to find Toki and Abigail.
The band considers giving up and making a run for it, but resolve to complete their mission. They succeed in locating Toki and Abigail and free them. They are confronted once more by the Assassin, but they stand by Toki, and their brotherhood activates the power of the Doomstar, ascending them to inhuman heights and finally killing the Metal Masked Assassin. Magnus sees the error of his ways and realizes he is the villain. He stabs himself in the heart, taking his own life as recompense for his sins against his former bandmates.
In the conclusion, Dethklok celebrates their success with a massive concert, Nathan and Abigail become a couple, and Offdensen becomes the new high priest of the Church of the Black Klok. However, at the very end, a sleeping Murderface is shown being slowly overtaken by some sort of dark energy, emanating from the wound to his wrist.
- Brendon Small as Nathan Explosion, Skwisgaar Skwigelf, Pickles, William Murderface, Young Toki Wartooth, Charles Offdensen, Ishnifus Meaddle, Edgar and Eric Jomfru, Magnus Hammersmith, Dr. Rockzo, Dethklok Minute Host, all Klokateers, Church of the Black Klok monks, old guitar teacher, strange man from Depths of Humanity, fans
- Mike Keneally as Toki Wartooth
- Malcolm McDowell as Vater Orlaag
- George "Corpsegrinder" Fisher as Metal Masked Assassin
- Raya Yarbrough as Abigail Remeltindrinc, old groupie
- Mark Hamill as Mr. Salacia, Senator Stampingston
- Victor Brandt as General Crozier
- Jack Black as Dethklok's original manager, fat blogger
- Ulrich Wild as Bald Fan
The score was composed by Brendon Small. A 50-piece orchestra was composed by Bear McCreary. The special contained several guest voice actors such as George "Corpsegrinder" Fisher and Jack Black.
The primary writers for the special were Brendon Small, Janine Ditullio, and Mark Brooks, with the teleplay by Brian Posehn and Brendon Small. Tommy Blacha did not reprise his roles for Toki Wartooth, William Murderface, and Dr. Rockzo; instead Toki Wartooth was sung by Mike Keneally (with Brendon Small singing young Toki), while Murderface and Dr. Rockzo were sung by Brendon Small.
The special premiered on October 27, 2013, on Adult Swim, and the next day became available for download on Amazon Instant Video. Rumors circled that the special would conclude the Metalocalypse series, as creator Brendon Small had stated in the past that his intention would be to do the fourth season and a movie, then end the show. Due to the cliffhanger ending, it was speculated that the series will continue. Brendon Small has since said that there is still more of the story to tell, and the special was intended as the conclusion of Season 4.
Main article: The Doomstar Requiem
On October 29, 2013, the score for the special was released on a full-length studio album by Dethklok. The album also includes "making of" feature. For the first time, Dethklok's live guitarist Mike Keneally is featured on a studio album. The first single off the album, "Blazing Star", was released on Loudwire on October 17, 2013.
- On amazon the special is titled "Doomstar Requiem Episode 1".
- Most of the weapons given to the band by Jomfru are used in the "Giving It Back" section. Nathan uses the pen to write a check, Skwisgaar gives away the strings, Pickles the drum sticks, and Murderface the bass pick. The Hot Topic gift card is used later by Ishnifus to create a distraction.
- When Toki enters late for his "auditions appointments", his shadow on the floor has wings like he does during the duel.
- When Charles Offdensen is shown swearing an oath to protect the band, the bible he places his hand on has an inverted cross.
- Toki and Abigail develop a significant relationship during their captivity, and it has been hinted by Small that their relationship will continue to be seen in future episodes.
- Many fans of Dethklok from various seasons are shown to have auditioned to become Dethkloks new guitarist.
- In the opening sequence, everyone in the title credits that has an O in their name is replaced with the first o with an upside down pentagram
- This is the third time Dethklok has had no manager, and it is revealed that as of this episode Dethklok has had three managers.
- There is heavy emphasis of brotherhood thougout the opera, the Church of the Black Klok, Jomfru and his brother, Masked assassian and his brother, Klockateers and Dethklok themselves.
- Nathan is wearing shoes in Toki's flashback.
- The guitar solo in "Blazing Star" is to the same melody as Magnus's soliloquy in "Morte Lumina".