Dirk is a small-scale con artist whose latest scheme is working as a "Holistic Detective", who believes in the "fundamental interconnectedness of all things" and how that means that anything might prove useful in solving the whole cases of his clients — which, the way he sees it, means that he can do anything he likes, even take a three-week tropical vacation, and still charge it to the client as an expense. Of course, by Finagle's Law, somehow every mundane little job he starts off working on in each novel is somehow actually connected to the main plot, and he's the one who has to solve everything.
In this novel, while (supposedly) investigating the disappearance of an old woman's cat, Dirk stumbles into a plot by an extraterrestrial ghost to undo his death with a Time Machine. Too bad that would undo the creation of life on Earth! (It all Makes Sense In Context. Even the robot created to be religiously faithful in place of its creators.)
The novel started as a Recycled Script of Douglas Adams' Doctor Who story "Shada", which got stuck in Development Hell — several characters and locations are recycled from the episode wholesale. It also borrows heavily from Adams' Doctor Who story "City of Death".
There is a second Dirk Gently novel, The Long Dark Tea-Time of the Soul.
This novel provides examples of:
- Absent-Minded Professor: Professor Chronotis.
- Arbitrary Skepticism: Lampshaded. Richard expresses doubt at Dirk's theory involving ghosts. Dirk points out that he'd also doubted the time travel aspect until that was proven to him.
- Bavarian Fire Drill: Dirk's favorite way of getting places he shouldn't be.
- Beethoven Was an Alien Spy: Coleridge's poetry contains alien messages and Bach's music is transcribed from an alien instrument that synthesized music from the motion of the universe itself.
- Berserk Button: Michael Wenton-Weekes is described as "one of those dangerous people who are soft, squidgy and cowlike provided they have what they want." When the magazine he edited is taken away from him and given a successful Re Tool, he surprises himself by punching a fist through a window. And later, he kills the new editor in revengenote which allows the extraterrestrial ghost to take control of his body and use him in his plot...
- Beware of Hitchhiking Ghosts: The driver of a car is horrified when he sees the ghost of his boss appear in front the car. The ghost, on the other hand, is horrified to see another ghost in the car's passenger seat.
- Blue and Orange Morality: The malfunctioning Electric Monk, that believes in rapidly changing non-sequiturs. One of them being that shooting someone in the chest with a shotgun is a form of greeting.
- Captain Ersatz: Because of the first book's Recycled Script from "Shada", an abandoned Doctor Who episode, Reg is essentially a retired Time Lord with an unusual TARDIS. Richard and Susan are little more than re-named versions of Chris and Claire, respectively.
- Chekhov's Armoury: Dirk isn't wrong—everything that happens in these books is ultimately important. The Dirk Gently books embody this trope really because they are all about the interconnectedness of everything. Chekov's Armoury isn't just a device Adams used, it's what he based the whole book on. A poem, a conjuring trick, and a stuck couch in the first few chapters are all linked by the end.
- Cluster F-Bomb: Dirk and Richard both encounter a little boy with a swearword-to-sentence ratio approaching 1:1.
- The Eeyore: Michael is convinced he's being treated unfairly by the entire universe. Which makes him the ideal host for the alien ghost.
- ET Gave Us Wifi: The works of Johann Sebastian Bach are the sounds made by the computers on an alien flying saucer. Oh, and the long-lost second half of Kubla Khan was written while Samuel Taylor Coleridge was possessed by the ghost of an alien from said flying saucer, and was designed to subtly convince the reader to give themselves up to possession by said ghost.
- The Fog of Ages: Professor Chronotis suffers from this.
- From the Mouths of Babes: After announcing despairingly that the mystery must have a solution that even a child could see, Dirk goes out and asks a child, who immediately gives him what turns out to be the correct solution.Child Selected At Random: It's obvious, 'e must 'ave a time machine.
- Gag Nose: The dean of St. Cedd's College has an enormous nose. Richard is the first person who ever talked to him in seventeen years, three months and two days, five hours, nineteen minutes and twenty seconds (he counted) because everyone else was afraid of laughing right in his face.
- Genre-Busting: DGHDA is described by its author as a "detective-ghost-horror-who dunnit-time travel-romantic-musical-comedy-epic".
- Ghostly Goals: Gordon is able to move on after finishing his phone call to his sister Susan that he was killed in the middle of.
- Historical In-Joke: The novel ties together the origins of life on earth, Samuel Taylor Coleridge's epic poem "Kubla Khan", the extinction of the dodo, the career of Buxtehude, and dozens of other epochal or trivial events into an excellent approximation of a coherent plot.
- Impersonating an Officer: Used by Dirk as part of his Bavarian Fire Drill.
- Irrevocable Message: While leaving an apologetic message on his girlfriend's answering machine, Richard makes a promise that he immediately realises he can't keep and will only make the situation worse. Which he attempts to revoke by breaking into his girlfriend's apartment (while possessed by a ghost). And he ultimately succeeds, for altogether more convoluted reasons ...
- Laser-Guided Karma: Whatever Dirk claims to believe in order to extract cash from gullible people invariably turns out to really be true, but always in such a way that he looks bad, sometimes in such a way that he suffers physical or emotional trauma, and never in such a way that he gets the money.
- Literal-Minded: The Electric Monk killed someone named Gordon Way after misinterpreting a porter telling him to "shoot off".
- Literary Work of Magic: Samuel Taylor Coleridge's poems contain secret messages conveyed to him while he was under the influence of an alien ghost, as part of plan to wipe out the human race.
- Magicians Are Wizards: Reg performs an impossible magic trick to entertain a restless little girl at a formal dinner. Nobody but Dirk realizes that it's genuinely impossible, and he decides to investigate.
- Mike Nelson, Destroyer of Worlds: The extinction of the dodos was caused by Reg trying to prevent the extinction of the coelacanth.
- Misapplied Phlebotinum: Reg has a time machine and he uses it to catch television shows that he missed.Dirk: You have a time machine and you use it for... watching television?
Reg: Well, I wouldn't use it at all if I could get the hang of the video recorder.
- No Badge? No Problem!: Dirk does this as part of the workings of his Holistic Detective Agency when he has a mystery that actually interests him rather than one that involves tricking old ladies into letting their cats loose. The local inspector Sergeant Gilks takes a rather dim view of this... along with Dirk's tendencies to be involved in highly peculiar situations that Gilks does not like very much in the first place, as well as his habits of removing or obscuring evidence...
- No Celebrities Were Harmed: Gordon Way and WayForward Technologies are thinly-disguised spoofs of Sir Clive Sinclair and Sinclair Research respectively.
- Not-So-Phony Psychic: When he was in university, Dirk posed as a psychic, was uncannily right, and got arrested for it. He now spends a lot of time insisting to people who were there that he's not psychic. Usually they don't believe him and his reputation often precedes him. Played with, as Dirk built his reputation for being a psychic at university by repeatedly and publicly insisting he was not, in any way, shape, or form, a psychic. Which nobody had ever actually suspected him of being until he started denying it.
- This is Lamp Shaded in the radio dramatization when Dirk astonishes another character by making a prediction that almost immediately comes true.Dirk: It's just my depressingly accurate powers of prediction.
Police Officer: You could clean up betting on the ponies with that.
Dirk: That's the depressing part — I can't!
- This is Lamp Shaded in the radio dramatization when Dirk astonishes another character by making a prediction that almost immediately comes true.
- One Steve Limit: Averted with Gordon's sister Susan and secretary Susan at the office.
- Only Sane Man: Richard Macduff. Richard is the only one who finds a horse randomly appearing in Reg's bathroom a bit peculiar. He's also the only one who notices that the way his sofa is stuck in his staircase is geometrically impossible. He fails to notice that Reg's magic trick is impossible though, preferring to assume there's a more mundane explanation.
- Our Ghosts Are Different: A ghost's intangibility (along with its visibility) flickers in and out, allowing them to manipulate objects only at certain times.
- Our Time Machine Is Different: Reg's time machine is his entire office. The controls are an abacus, and the whole thing stops working after he hired someone to fix the phone.
- Oxbridge: Features St. Cedd's College, a fictional college at the real Cambridge University.
- Peekaboo Corpse: A ghost discovers his own corpse in a cupboard. And faints.
- Perpetual Poverty: Dirk never seems to have much money — a Running Gag is his secretary quitting over not getting paid — and most certainly never gets paid by his clients. He manages to stay in his office, flat, etc, through arranging the situation so that it would be more inconvenient to actually eject him or force him to pay than just let him be and hope that he'll pay some day.
- Phone Call from the Dead: A guy makes a car phone call and starts talking into the answering machine, then gets killed. Just later his ghost tries to communicate by talking through the phone, which is recorded on the answering machine as well.
- Plug 'n' Play Technology: The time machine can automatically adapt itself to give information and receive instructions from any appropriate device connected to it, or even placed near it. Its owner says that this feature probably comprises more of the device's workings than those required to perform its actual function.
- Religious Robot: The Electric Monks, which were designed as a labour-saving device that would believe things so that their owners didn't need to; a malfunctioning one ends up involved in the plot.
- Ripple Effect-Proof Memory: More prevalent here than usual; you have to lead a very sheltered life to never notice little discrepancies between your memories and reality.
- Rubber-Band History: Samuel Taylor Coleridge finished writing "Kubla Khan" and nobody's ever heard of Johann Sebastian Bach's music. By the end of the novel, both of these have become our familiar versions of history. There's also a cautionary anecdote about inadvertent time travel resulting in the extinction of the dodo.
- San Dimas Time: There's a telephone in the time machine, which can be used to straightforwardly communicate with the present. (On the other hand, there's a sequence where a character goes on a six-week trip into the past, and returns moments after he left.)
- Schmuck Bait: Dirk told his fellow students he wasn't psychic, no matter how much money they offered him to predict the upcoming exam questions. Subverted, because he unintentionally predicted exactly what the questions would be.
- Shout-Out: A few to Adams' other series:
- Richard asks Dirk if he always carries a towel around.
- Reg says that moving through time and space is closer than going to the chemist's—the opposite comparison that the Guide makes, "I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space, listen..."
- Starfish Aliens: Living members of the alien race never appear, but the description in the opening scene reveals they have purple crinkly skin, a single eye but multiple mouths and noses, and a variable number of legs, but always a prime. The reason the Electric Monk looks exactly like a Caucasian human is so that no-one could possibly mistake it for a real person.
- Steven Ulysses Perhero: Albert Ross
- Suspiciously Specific Denial: Deliberately invoked by Dirk at university. By carefully denying the most extraordinary things, he convinces his fellow students that he's a psychic, mystic, telepathic, clairvoyant, psychosassic, vampire bat.What did "psychosassic" mean?
It was his own word and he vigorously denied it meant anything at all.
- Take That!: The Electric Monk is a deliberate slap in the face to all organized religion.note The deluxe model in particular is "capable of believing things they wouldn't believe in Salt Lake City."
- Talking in Your Sleep: How Dirk's supposed psychic powers manifested.
- This Is a Work of Fiction: Holistic Detective Agency disclaims any resemblance to real people "living, dead, or wandering the night in ghostly torment".
- Time Abyss: The alien ghost has been around since before life on Earth began. He is understandably unhinged.
- Trigger Phrase: "my maiden aunt from Winnipeg"
- Viewers Are Geniuses: Unless you are quite familiar with the works of Samuel Taylor Coleridge ("Kubla Khan" and the story of the "Person from Porlock" in particular), you will not understand the ending at all. To make perfect sense, the novel also requires you to remember minor details from early in the book that eventually become major plot points (as mentioned above under Chekhov's Armoury), and several clues are left to the reader to connect themselves.
- What Have We Ear?: One of the conjuring tricks Reg does.
- Who Wants to Live Forever?: Or, technically, be dead and floating around as a ghost forever.