From publisher blurb:
Shinkansen is an adventure set piece for modern d20 games. Set pieces are a concept from films: a scene or sequence with escalated stakes and production values, as appropriate to the genre. For instance, in an action film, a set piece might be a helicopter chase amid skyscrapers. In a musical, a set piece might be a show-stopping dance number. In a comedy, a set piece might find the claustrophobic hero on an increasingly crowded bus, until he can’t take it anymore. Done right, set pieces are moments you remember weeks after seeing a movie...memorable
nuggets that become the highlights of the tale.
In the context of modern d20 games, a set piece is an adventure sequence that can be plugged in to a larger adventure, with notes offering suggestions for adapting the set piece to the genre of your particular campaign.