[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/diamond_brothers.jpg]]

->''"Tim's first job was to find some rich lady's pedigree Siamese cat. He managed to run it over on the way to see her. The second job was a divorce case - which you may think is run-of-the-mill until I tell you that the clients were perfectly happily married until he came along. There hadn't been a third case."''
-->-- '''Nick Diamond''', ''The Falcon's Malteser''

Series of detective/comedy novels by Creator/AnthonyHorowitz, featuring would-be private eye Tim Diamond (real name Herbert Simple) and his kid brother Nick. Despite believing himself to be a genuinely brilliant detective, Tim is utterly hopeless, and all of the cases are solved by Nick him despite never getting any credit, with the occasional help or hindrance of supporting characters Chief Inspector Snape of Scotland Yard and his sidekick Boyle.

!!Novels:
* ''Literature/TheFalconsMalteser'' (1986)
* ''Public Enemy Number Two'' (1987)
* ''Literature/SouthBySouthEast'' (1991)
* ''Literature/WhereSeagullsDare'' (2022)

!!Novellas:
* ''The French Confection'' (2003)
* ''The Blurred Man'' (2003)
* ''I Know What You Did Last Wednesday'' (2003)
* ''The Greek Who Stole Christmas'' (2008)


!!Short Stories:
* ''The Double Eagle Has Landed'' (2011)

The novellas have been collected in ''Three of Diamonds'' (later retitled ''Four of Diamonds'' with the release of ''The Greek Who Stole Christmas''). The first novel was adapted for the big screen in 1989 under the name ''Just Ask For Diamond'', and ''South by South East'' was made into a TV series in 1991 using the same cast. A final novella intending to act as a GrandFinale, ''The Radius of the Lost Shark'', has been in DevelopmentHell since at least 2003, with Horowitz still promising it will be published as recently as 2020. A short story, [[https://www.anthonyhorowitz.com/extras/feature/short-story-the-double-eagle-has-landed "The Double Eagle Has Landed"]], was published in the Guardian in 2011, and in 2020 Horowitz announced a new story, ''Where Seagulls Dare'', was to be released online chapter-by-chapter during the [[UsefulNotes/CoronavirusDisease2019Pandemic 2020 coronavirus pandemic]]; it was later released as a book, the first full-length entry in the series in over 30 years.
----
!!Provides Examples Of:
* AdultsAreUseless: Nick manages to outwit each and every adult he encounters, be it the police, his older brother, or a master criminal.
* AlwaysSecondBest: In ''I Know What You Did Last Wednesday'', the mysterious killer, [[spoiler:Captain Randle/Johnny Nadler]], came second in every subject in school and never really stood out of the group he was part of in school (which consisted of everybody who came first). He doesn't respond too well; [[spoiler:he lures everybody who bested him to a secluded island and kills them with cruel and ironic death traps which somehow relate to the subject they beat him in (poisoned the person who came first in Chemistry, stabbing the person who came first in French with a model of the Eiffel Tower, etc.)]].
* BaitAndSwitchGunshot: PlayedForLaughs at the climax of ''The Falcon's Malteser''.
* BittersweetEnding: Most of the tales. The case is solved, but the brothers get no recognition, and any bit of potential happiness they have doesn't last long.
** With the ending of ''The Falcon's Malteser'', [[spoiler:the MacGuffin has been stolen by Nick's sidekick, but she sends him a diamond that he and Tim exchange for money. They have enough to go on holiday, but Tim breaks his leg before they get on the plane and the rest of the money is spent on his treatment.]]
** ''The Blurred Man'' ends with [[spoiler:the villains caught and arrested, but (yet again,) Scotland Yard aren't appreciative (the villains even nearly shot at their helicopter before the brothers jumped at them), and Nick and Tim have to tell Joe Carter the truth about his philanthropist pen pal.]]
* BlackDudeDiesFirst: Inverted - Mark Tyler, the only black character in ''I Know What You Did Last Wednesday'', is the final character to die (albeit by a matter of seconds).
* BlatantLies: There are several examples, mostly from Nick trying to cover up Tim's incompetence, but the best example has to be in ''Public Enemy Number Two'', when Tim announces to a group of criminals he and Nick are meant to infiltrate that he is a private detective; as the mood rapidly turns frosty, Nick makes up a spur-of-the-moment tale that he is a private investigator of water, "having to check there is enough H". Incredibly, this works.
* {{Cloudcuckoolander}}: Tim, who's often the last person in the room to work out a villain's crime just as the villain prepares to kill them.
* CluelessDetective: Tim, often taken to extremes; the one time he manages to solve a case, not only is it completely by accident, he's on the run from the law at the time, and he promptly destroys the priceless Ming vase he was meant to be looking for by accident. The logo of the series features the words 'Diamond Brothers Detective Agency', with a scratch over the first 't' in 'Detective' making it seem like it actually says 'Defective'.
** Deliberately invoked by the villain of ''The Greek Who Stole Christmas'', who hires Tim to investigate the case knowing his reputation as the worst detective in London.
* ComicBookTime: The original books came out in the late 80s and early 90s. The more recent novellas, released over a decade later, have Tim and Nick at the same age but feature modern-day concepts such as the London Eye.
* CourtroomAntics: Subverted by ''Public Enemy Number Two'': when Tim is called as a witness to Nick's trial, he does proceed to make a complete mockery of the legal system by saying increasingly stupid things, but he is completely unaware he's doing so and it more or less secures Nick's conviction.
* DeadpanSnarker: Nick.
* DoNotCallMePaul: Tim gets very touchy about people using his real name.
* DirectLineToTheAuthor: The introduction to ''Three of Diamonds'' claims that Horowitz was approached by the Brothers to write their adventures up as novels. (A later version in one of the ''Two of Diamonds'' printings explained why the books are written in the first person from Nick's perspective by saying that Nick wrote the manuscript, then Horowitz rewrote it.)
* EarlyInstallmentWeirdness: The first book refers to Tim as "Herbert" (his real name) throughout, and isn't quite as comedic in tone as any of the others.
* GenreBlind: Tim.
* GenreSavvy: Nick.
* HisNameReallyIsBarkeep: Betty Charlady [[spoiler:Subverted, in that it turns out that's not her real name]]
* HurricaneOfPuns
* HypercompetentSidekick: Nick. Whilst Tim faints at the sight of blood and is constantly caught at the scenes of murders holding incriminating evidence (typically the murder weapon), he solves every single case.
* IncrediblyLamePun: Many times, even the titles of the books.
* KidHasAPoint: The 13/14-year-old Nick Diamond, the only level-headed member of he and his brother's partnership, who solves everything, even before the police of Scotland Yard, infuriating them.
* LastNameBasis: Snape and Boyle; in the former's case it turns out that his first name is [[EmbarrassingFirstname Freddie]].
* MalevolentArchitecture: The brothers get invited to an island mansion which is rigged with [[DeathTrap death traps]] designed to kill the people invited.
* MeaningfulName: [[spoiler:In the final chapter of ''Public Enemy Number Two'', Nick realises his French teacher, Palis, is the BigBad when he translates his nickname, the Fence, into French:]]
-->''[[spoiler:Palissade.]]''
-->''[[spoiler:Palis.]]''
* OddNameOut: The first six books' titles are all parodies of crime novels and movies such as ''Film/{{The Maltese Falcon|1941}}'' and ''Film/NorthByNorthwest''. The last book's title is taken from ''Literature/HowTheGrinchStoleChristmas''.
** Similarly, Nick's narration in that book implies that the next book (if there is one) will be called [[Film/RaidersOfTheLostArk The Radius of the Lost Shark]].
* ParentalAbandonment: Inverted in that Nick chose to abandon his parents when they emigrated to Australia.
* PerpetualPoverty: Sort-of. The brothers do actually make the odd windfall - they just always [[DiabolusExMachina lose it]] not long afterwards. Nick even [[GenreSavvy predicts this]] in the first book, noting that, having finally gotten enough money for a holiday, they'll probably have to spend it all on treatment after Tim inevitably breaks his leg or something.
* PianoDrop: Nick escapes from the flat he's imprisoned in by dropping a piano on the villains returning there after finding he's lied to buy himself time.
* PlotBasedPhotographObfuscation: ''The Blurred Man'', [[spoiler:where the two criminals of the book have been running a charity using the fake persona of "Lenny Smile". When somebody asks for a photo of Lenny Smile, one of the criminals dresses up as him in a deliberately out-of-focus photograph.]]
* PoliceAreUseless: Snape and Boyle, and the rest of Scotland Yard (Scotland Yard, by the way, is the most prestige police system that would track down the worst criminals, along with UsefulNotes/MI6). Nick (and Tim) are seen as nuisances that get in the way of their cases. Unfortunately, Nick's intuition and intelligence force them to back down. One would think that the Diamond brothers' work would get them recognition or any other reward, but no -- each episode begins with Tim and Nick starving in their fixer-upper apartment waiting for a client with a pile of money.
* PunnyName: In the first book alone there are two Germans called [[Creator/GratuitousGerman Gott and Himmel]], a FemmeFatale called [[Creator/LaurenBacall Lauren]] Bacardi, and a charlady called Betty Charlady.
* ReunionRevenge: The plot of ''I Know What You Did Last Wednesday''.
* RunningJoke: Tim's inability to remember a client's name properly; 'Mr Naples' becomes 'Mr Venice', 'Mr Navels' and 'Mr Nipples' within the course of the first chapter, 'Johnny Powers' becomes 'Johnny Flowers', 'Mr Hammill' becomes 'Mr Camel', 'Mr Hubble', 'Mr Rubble' and 'Mr Rabble', etc. etc.
* StatusQuoIsGod: No matter how great the reward is for solving a crime, by the beginning of the next book the Brothers are destitute again.
* ThoseTwoGuys: Snape and Boyle, inspectors from UsefulNotes/ScotlandYard. They loathe the two brothers (mostly because the brothers do most of the work for them, leaving them to arrest the criminals). Nick comments his frustration about the two of them never thanking them when everything's solved.
* TitleDrop: All the titles of the books, from "I Know Who You Killed Last Wednesday" to "The Falcon's Malteser" to even "South by Southeast" get dropped in context.
* TooDumbToLive: Tim.
* TwistEnding: Once in each of the first three novels.
** [[spoiler:In ''The Falcon's Malteser'', when Nick finds that Lauren has gotten to the diamonds before him.]]
** ''Public Enemy Number Two'': [[spoiler:Nick realises his French teacher is the BigBad. He and Nick end up on the roof of the school, in which the teacher falls to their death, impaled on fence just as the police arrive.]]
** ''South by South East'': [[spoiler:Nick realises that Tim's girlfriend is the BigBad.]]
* WireDilemma: A variation appears in ''Public Enemy Number Two'', with a switch Nick has to decide whether to move left or right.
----