What happens in The Hitchhiker's Guide to the Galaxy Live?
The show opens in The Horse and Groom, a London pub recreated in Riverside Studio 2. Ford Prefect — a writer for an interstellar travel guide who has been stuck on Earth for fifteen years researching its entry — is throwing his friend Arthur Dent a farewell party. The show added a romantic element from the later novels: Arthur's love interest Fenchurch is also present, and she and Ford share a karaoke battle as the show's opening musical number.
The destruction of Earth
Mid-pint, the Vogon Constructor Fleet arrives in orbit to demolish Earth to make way for an interstellar bypass. Prostetnic Vogon Jeltz (pre-recorded voice: Sanjeev Bhaskar) makes the announcement; the Newsreader (pre-recorded voice: Samira Ahmed) confirms it. Ford reveals to Arthur that he is in fact an alien, produces an electronic thumb, and the two hitchhike onto the Vogon ship just as Earth is destroyed.
Aboard the Heart of Gold
After surviving Vogon poetry — the third-worst in the universe — Arthur and Ford are flung into space, where they are improbably rescued by the Heart of Gold, a stolen spaceship powered by an Infinite Improbability Drive. Aboard are Zaphod Beeblebrox (Lee VG), the two-headed President of the Galaxy, his girlfriend Trillian (pre-recorded voice: Lenora Crichlow), and Marvin the Paranoid Android (puppet, operated by Andrew Evans). The audience moves with them.
The Vogon ship, the mice, and the meaning of life
The show takes in the encounter with Slartibartfast (Richard Costello), the planet-designer responsible for Earth's fjords, and the eventual reveal that Earth was an enormous computer constructed by hyper-intelligent inter-dimensional beings (who appear to humans as mice) to discover the question to the Ultimate Answer of Life, the Universe, and Everything (which is, as readers will know, 42). The mice now want Arthur's brain, since he carried the last microsecond of the computation.
The audience as hitchhikers
The show's promenade structure meant audiences were treated, throughout, as fellow hitchhikers — addressed directly by Ford, Marvin, and the rest, given prompts to interact, and physically moved between the show's environments. The framing was that the audience were also stranded in space and trying to find their way home. The ending — without spoiling specifics — drew on the broader Hitchhiker's lore of resolved-but-unresolved cosmic uncertainty.