Book Four: Duet
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.
All Episodes
Episode 1
The Twin Tapes
April 15, 2021
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.
Episode 2
The Iceberg Car
April 15, 2021
Waking up on the train together, Ryan and Min-Gi are met by Kez, whose mistake has left the boys in a predicament.
Episode 3
The Old West Car
April 15, 2021
Arriving in a Wild West town, Ryan, Min-Gi, and Kez attempt to escape the locals.
Episode 4
The Pig Baby Car
April 15, 2021
Ryan and Min-Gi are forced to satisfy Pig Baby with the perfect dessert.
Episode 5
The Astro Queue Car
April 15, 2021
With a growing rift forming between them, Ryan and Min-Gi attempt to convince a bouncer to let them enter the rave.
Episode 6
The Party Car
April 15, 2021
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.
Episode 7
The Art Gallery Car
April 15, 2021
The boys' disintegrating relationship finally comes to a head when they end up in a haunted art museum with seemingly no exit.
Episode 8
The Mega Maze Car
April 15, 2021
As the duo nears Kez's home, they are forced to contend both with all their enemies and their messy relationship.
Episode 9
The Castle Car
April 15, 2021
Having finally arrived at Kez's home, Ryan and Min-Gi learn of her biggest secret and regret.
Episode 10
The Train to Nowhere
April 15, 2021
Ryan and Min-Gi are forced to face the truth and a final challenge if they ever want to go home.