Book Four - Duet

**Book Four - Duet** is the fourth season of the Cartoon Network series *Infinity Train* and serves as a standalone prequel to the three previous books. It premiered on April 15, 2021, on HBO Max.

Min-Gi and Ryan are childhood best friends who dreamed of performing in a band and traveling across Canada, together. After a sudden falling out splits them apart, both find themselves aboard the mysterious Infinity Train. Lost and confused, they meet Kez, a free-spirited concierge bell, who accompanies them on their journey. As tensions rise and old wounds come to light, both Min-Gi and Ryan must decide if they can work together or else risk losing themselves forever aboard the Infinity Train.

Book Four was formally revealed through HBO Max's twitter on February 17, 2021.

The trailer was revealed on Twitter by Entertainment Weekly on March 11, 2021. Which also confirmed that Book 4 will be the final season. Owen Dennis revealed the season's full title and introduced the main characters on Twitter. Book 4 was not intended to be the final one when it was written. Dennis and the writing staff had enough stories to last eight seasons and expressed a desire to continue the show if given the opportunity.

HBO continued to advertise Infinity Train. On March 25, 2021 the poster for Book 4 and a more detailed synopsis (the one above) was released on HBO Max's Twitter. Then on April 8, 2021 a exclusive clip was released on YouTube.

## Cast and Crew

### Voice Cast

Main

* Sekai Murashige as Ryan Akagi
* Johnny Young as Min-Gi Park
* Minty Lewis as Kez

Supporting

* Jeremy Crutchley as One
* Lena Headey as Amelia Hughes
* Kate Mulgrew as Samantha
* Kari Wahlgren as Parka Denizen 1 and Parka Denizen 2
* Keith Ferguson as Parka Denizen 3
* Margo Martindale as Caterpillar Sheriff/Judge Morpho
* J.K. Simmons as Pig Baby
* Audrey Wasilewski as Cow Creamer
* Owen Dennis as Brando
* Donald Faison as Beehive
* Thomas Lennon as Spiceman
* Margaret Cho as Morgan

### Production Crew

writers

* Justin Michael (eps: 1, 6, and 8)
* Lindsay Katai (eps: 2, 4, and 9)
* Alex Horab (eps: 3, 5, 7, and 10)

## Gallery

*Click here to view this page's gallery.*

## Videos

Infinity Train Book 4 - Teaser - HBO MaxInfinity Train Book 4 - Official Trailer - HBO MaxBook 4 Exclusive Clip - Infinity Train - HBOMaxInfinity Train Book 4 - Opening Scene - HBO MaxTrain to Nowhere Music Video - Infinity Train - HBO Max(Spoiler warning)Infinity Train - All the Feels from Books 1-4 - HBO MaxInfinity Train - All The Songs in Books 1-4 - HBO Max
## Trivia

* Prior to the reveal of season's plot, Owen Dennis joked on Twitter that the fourth book's title was "Demon Slayer", a reference to the anime of the same name and its 2020 film *Demon Slayer: Kimetsu no Yaiba the Movie: Mugen Train*, which in some territories was known as *Demon Slayer: Infinity Train*. Dennis claimed it was the show's way of getting revenge on said anime. A month later he confirmed the official title of "Duet" after the official trailer was released.
* Owen Dennis believes that Book 4 could be binged or watched at the viewers' own pace. Compared to the previous books, Book 4 works better binged. Ultimately, he doesn't have a preferred way for fans to watch it and hopes people enjoy it.
* Dennis noted that Book 4 was very much written with the idea of subverting the previous three seasons: they were aware the audience was expecting some form of traumatic event or death, and wished to do the opposite after the dark tones of Book 3.
* Book 4 was initially planned to be about two bank robbers from the old west.
* Dennis hinted the story of Book 4 way before it was officially confirmed during the Book 3 AMA. It was cleverly worded as a joke.

### Continuity

* This is the first season since Book One to not have a main character be a character introduced in a previous season.
* This is the only book not to feature Ghoms.
* The book is set in the mid- to late 1980s.
	+ As such, it is the only book where Grace and Simon do not appear, as they have not yet been born.
	+ This is also the only book where Samantha makes no appearances alongside Randall, as they do not meet until "The Beach Car".
	+ A younger Amelia learns how the train works from One-One. Her rise to power is inferred throughout the season.

## References

1. ↑ https://www.youtube.com/watch?v=T\_eiKWvQxZ8
2. ↑ Synopsis from the Polygon.
3. ↑ HBO max book 4 audio teaser.
4. ↑ Entertainment Weekly tweet.
5. ↑ "While this wasn't the intended final season of Infinity Train..."
6. ↑ "The new season is gonna be called "Infinity Train: Demon Slayer" We're takin' it back, people!" - Dennis
7. ↑ Owen Dennis's tip on how Book 4 should be watched.
8. ↑ Dennis on subverting viewer expectations.
9. ↑ Dennis on the effect Book 3 had on the crew.
10. ↑ From two partners in crime to two rockers of all time!
11. ↑ "No, the protagonists of season 4 are gonna be the rock couple from the campfire car arguing about vacation spots. How do these rock who are separating emotionally still navigate their lives together? Should they? Which vacay spot has the restaurant where one rock loves the brownies and the other rock loves the live music from local Canadian prog-rock bands? Should they stay at the cabin with all the pictures of baby pigs on the walls, or the cabin that had the bug zapper fire hazard because all the moths hadn't been cleaned out of it?" - Dennis