Book Four: Duet

2021 · 10 episodes · 1h 50m in all · 9.3/10

Childhood friends with opposing personalities, Mingi and Ryan, dream of becoming rock stars but find themselves on the Infinity Train. They explore the locomotive's inner puzzles — and their own relationship — in order to return home, together.

1. The Twin Tapes
15 Apr 2021 · 11 min · 9.7/10
Once great friends, Ryan and Min-Gi's relationship slowly dissolves over the course of years of disgruntlement, culminating with their reunion in the restaurant.
2. The Iceberg Car
15 Apr 2021 · 11 min · 8.3/10
Waking up on the train together, Ryan and Min-Gi are met by Kez, whose mistake has left the boys in a predicament.
3. The Old West Car
15 Apr 2021 · 11 min · 8.5/10
Arriving in a Wild West town, Ryan, Min-Gi, and Kez attempt to escape the locals.
4. The Pig Baby Car
15 Apr 2021 · 11 min · 8.0/10
Ryan and Min-Gi are forced to satisfy Pig Baby with the perfect dessert.
5. The Astro Queue Car
15 Apr 2021 · 11 min · 9.5/10
With a growing rift forming between them, Ryan and Min-Gi attempt to convince a bouncer to let them enter the rave.
6. The Party Car
15 Apr 2021 · 11 min · 9.0/10
With their instruments back, Ryan and Min-Gi have to play their first show since they were kids, but it's no easy emotional feat.
7. The Art Gallery Car
15 Apr 2021 · 11 min · 10.0/10
The boys' disintegrating relationship finally comes to a head when they end up in a haunted art museum with seemingly no exit.
8. The Mega Maze Car
15 Apr 2021 · 11 min · 10.0/10
As the duo nears Kez's home, they are forced to contend both with all their enemies and their messy relationship.
9. The Castle Car
15 Apr 2021 · 11 min · 10.0/10
Having finally arrived at Kez's home, Ryan and Min-Gi learn of her biggest secret and regret.
10. The Train to Nowhere
15 Apr 2021 · 11 min · 10.0/10
Ryan and Min-Gi are forced to face the truth and a final challenge if they ever want to go home.