James May takes on one of his supersized toy challenges: building the longest continuous model railway track ever attempted. The film follows the planning and construction across a stretch of countryside, recruiting model-train enthusiasts and hobbyist clubs to lay track section by section toward a record distance. May narrates the process himself, working through the engineering problems that come with scaling up a tabletop hobby to a real landscape, from power supply over long distances to keeping dozens of locomotives running in sync. The build culminates in a race along the finished track, testing whether the record-length line actually works as intended rather than just existing on paper. Interviews with the enthusiasts who show up to help fill in the culture around model railways, and the film treats their obsession seriously rather than as a punchline. It is part of a series in which May applies the same stunt logic to other traditional toys, but this episode stands on its own as a straightforward account of one very large model train set.