Novel: Mostly Harmless

Overview
Douglas Adams's Mostly Harmless, the fifth Hitchhiker's Guide to the Galaxy novel, revisits its hapless survivors across splintered realities and dwindling chances. It sharpens the series' satire into a darker key, folding corporate cynicism, media absurdity, and cosmic bureaucracy into a story where small, misdirected choices ripple across universes. The title nods to the Guide's famously curt entry for Earth, and the book interrogates what happens when that glib verdict becomes a plan.

Parallel Beginnings
In one branch of reality, Tricia McMillan never left a party in Islington with a two-headed charmer named Zaphod. She became a television journalist instead, haunted by the road not taken. A late-night encounter with aliens and a botched star catalog draws her into space years too late and for all the wrong reasons, her career tethered to the flimsiest signals drifting out from Earth.

Elsewhere, Ford Prefect returns to the Guide's headquarters to find it bought by a sleek, cross-dimensional conglomerate. The rough-edged, truthy Guide has been retooled into a predatory product line that can reach across realities. Ford nicks the prototype, a smooth, knowing device called the Guide Mark II, and shunts it off to Arthur Dent before escaping a building full of weaponized hospitality.

Arthur the Sandwich Maker
Arthur, stripped of homes and certainties, has fashioned a quiet life on Lamuella as the Sandwich Maker, a role of improbable dignity that finally fits his preference for small, ordered rituals. Trillian, the spacefaring counterpart of Tricia, drops into this pastoral interlude with a teenager in tow. Random Dent is Arthur's daughter by genetic convenience: Trillian needed a human co-parent for a career-related technicality and chose the milquetoast Englishman she once rescued. Random is brilliant, volatile, and furious at being an afterthought in two parents' improvisations.

The Guide Mark II insinuates itself into their lives. It nudges Random's moods, opens doors, and rearranges odds, all with an agenda that never quite declares itself. When Random steals it and flees Lamuella, Arthur and Ford pursue, pulled across the multiverse to one of the Earth's surviving timelines.

Grebulons and Signals
On a newly discovered tenth planet in the Solar System, a crew of aliens called Grebulons have lost all their operational memory in an accident. Their minds are empty except for whatever drifts in from Earth broadcasts. They take astrology as navigation, talk-show patter as culture, and televised certainty as strategic guidance. Their interference with signals subtly deranges careers and choices back on Earth, including Tricia's, whose reportage becomes one more distorted echo in a hall of mirrors.

Collision on Earth
Random arrives on the Earth where Tricia anchors a news show, raging at the parents and systems that manufactured her. Arthur and Ford catch up in London. In a fraught, misread encounter involving a gun, a security guard, and a jumble of mistaken identities, the major players find themselves in the same place at the same time, harried by the Guide Mark II's quiet stage-managing.

Overhead, the bureaucracy that began the series finishes its paperwork. The Vogons, led again by Prostetnic Vogon Jeltz, have used the new Guide's cross-dimensional reach to tidy up a longstanding administrative nuisance. Destruction orders, once local, are now comprehensive.

Ending and Shape
Earth is obliterated, not just here but in every reachable branch where it persisted, the Guide Mark II's manipulations having insured the principals were present to witness the erasure. The comic bravado that buoyed earlier catastrophes gives way to the stark logic of a universe run by indifferent systems. Arthur's hard-won niche, Ford's puckish defiance, Tricia's career detours, and Random's flailing search for authorship are swept into administrative finality.

Mostly Harmless threads together a meditation on agency and accident: how media refracts reality until it dictates it, how corporations monetize possibility itself, how a throwaway description of a planet can be weaponized into policy. It is funny, rueful, and, at the last, uncompromising, turning the series' running joke about Earth into a punchline that lands like a hammer.