Postern of Fate (1973)

Plot: There's a plot?

Postern of Fate is free-association Agatha Christie, improvised like beat poetry in a smoky jazz cellar. That's another way of saying that it's regarded as her worst book ever, and yet... and yet... well, yet again, it's a book saved by Tommy and Tuppence.

Tommy and Tuppence have moved house. Tommy goes to London for meetings. Tuppence stays at home reading some old children's books and walking the dog. Occasionally they'll have lunch. Or dinner. Or argue with a tradesman. Sometimes Tuppence will go out to tea, or Tommy will reminisce. Occasionally, Tuppence will sit in a go-kart and roll down a hill. Once, the wheels fall off Tuppence's go-kart. This may be an attempt on her life. She's not really sure. Another time a pane of glass falls down near her. This may also be an attempt on her life. Again, no-one is really sure.

Tuppence sometimes tries to sort out the shed with the help of the local handyman Isaac, unless he's the gardener. But then again, Isaac is over 90, or in his 80s, or nearly 70. It's so hard to tell.

Sometimes, Tommy and Tuppence are investigating a crime that happened in the house during the first world war. Although, sometimes it happened later, or earlier. Or did it even happen at all?

In order to try and come to grips with this, Tommy goes to London for more meetings with people who either tell him about how much they enjoyed the plot of N or M, or mention that they were all in Passenger To Frankfurt. Meanwhile, Tuppence goes for more walks, and meets some children who also remark on how well she did in N or M.

There is mention of the Common Market.

Someone, at some point, god knows why, kills Old Isaac, so Tuppence needs to get a new gardener. Even though Isaac wasn't actually the gardener, but was there to help mend the conservatory. Luckily a man from the secret services tells Tommy that they'll send them a man who'll be an undercover agent and that they're not to trust anyone else. A lady turns up and offers to do the gardening. She also helps pour some coffee. Can you guess what happens next?

Luckily, eventually, it's all over. Someone, at some point, killed Mary Jordan. Tommy and Tuppence also appear to have thwarted an evil conspiracy, again. Or at least, we hear that the sinister conspiracy has moved to Bury St Edmonds. So that's okay.

What saves this book from being utterly utterly awful is that Tommy and Tuppence are as charming as ever. They're good company, even if they are telling you a story they don't seem to have a grip on. Christie's style remains similarly charming. In her 80s at the time, she wheeled this one out, her characters are addicted to reverie. The theme of this book is how unreliable memory and narrative are – appropriately enough, as Tommy and Tuppence are... well, let's just say that by this point Poirot is 120, Miss Marple is about 735, and lord knows how old Tommy and Tuppence are, or why Albert is mourning for an entirely different wife to the one he had last time.

Yes it's a bloody mess, but it's a charming one. If you can analyse why it's so adorable and compellingly readable then you're doing better than me. All I know is that I sat up night after night entranced by it, kids books, hearty stews, dog walks and all. There was an actual sigh of disappointment when something as vin ordinaire as a murder occurred. There's a great atmosphere here – similar to the magic of By The Pricking Of My Thumbs, that lovely feeling of Village Sinister, in which a discussion of magnolias can turn lethal at any moment.

The book is full of madness. There are clunking lines, there is banter that's eye-rolling (Tommy and Tuppence remove rubbish from inside a rocking horse. They call it surgery. Everyone laughs. No-one points out that Tuppence has earlier examined the horse and found it empty). There are clues that are never resolved. There is a greenhouse called KK. There is a significance hinted to at the real name of a Monkey Puzzle tree. And did I mention there's a go-kart?

And yet, it's somehow adorable. It's about Tuppence reading books and finding a long-lost mystery. It's about Tommy thinking. It's about a couple very much in love who can save the country and redecorate. And yes, very vaguely, it's about the Common Market.

Partners In Crime (1929)

Plot: What Tommy and Tuppence did next... was take the piss, frankly.

After the ripping yarn of The Secret Adversary, Tommy and Tuppence Beresford set out to solve crimes using the methods of other detectives as a set of literary parodies.

The whole idea was already waaay out of date when the stories were adapted for a baffled 1980s television audience. While Francesca Annis chews the scenery and a variety of hats, James Warwick turns up in a variety of mad costumes without explanation, including a priest's costume. If you're well-read in
your crime, you may just think “Why is he dressed as Father Brown?” but that'll be about it. By the time Francesca Annis dances through a health farm in a series of veils, you may indeed be ready to commit a crime yourself.

If you want to know the sources, Charles Osbourne's Life and Crimes of Agatha Christie features a handy grid... giving your an at-a-glance guide to a lot of mostly out-of-print and forgotten sleuths. You probably won't be much wiser, although you may go “oooh, I've read a couple”. There's also a lovely analysis here

The most interesting parody is when Tommy pretends to be Hercule Poirot, at which point you can only applaud Christie for being rather meta.

Hopelessly out-of-context, how do the stories themselves hold up? The nearest comparison I guess is The Big Four, although Partners In Crime is neither as mad nor as bad. Some adventures are joyous and atmospheric (The House Of Lurking Death), some are madcap John Buchan (The Sinister Stranger) or just madly Dr Nikola (Blindman's Bluff with its electrified floor).

However, just when your teeth grind together like a vintage gearbox, you'll be reminded how adorable Tommy and Tuppence are, or how well they work in an atmosphere of vague conspiracy and intrigue. What keeps this collection fun is that they're having a ripping time, which makes it all more than bearable. They're great company even on an off-day. More of which, next time.

The Secret Adversary (1922)

Plot: Can our heroes stop the evil Mr Brown from forming a Labour Government?

Crikey, has ever a book seemed more timely than The Secret Adversary, Christie's second work, which introduces Tommy and Tuppence and is her first mystery-thriller. It's a rip-roaring riot, full of much unintentional humour as our solid duo fight on behalf of the Conservative Party to unmask the sinister Mr Brown and save Great Britain from economic collapse.

Tommy and Tuppence are briliant, and this book is purely, wonderfully "Wodehousian" (an easy phrase for when two bright young things banter joyously throughout). When we first meet Tuppence she's wistfully trying to marry money and is gutted when she discovers her wartime general "keeps a bicycle shop in times of peace". "I'm so very fond of money," she says frequently.

Underneath all the froth, this is a reaction to the horrors of the First World War. Christie was inspired by the number of out-of-work soldiers who knocked at her door, and she composed a book about two such people cast adrift after the war, with a lot of breeding and no money. She rewards them for their charm with lots of nice meals and a stay at the Ritz as well as much excitement, as a contrast to a dull and meagre living as a door-to-door salesmen.

Instead she gives us two lovely people who call each other "old thing" and "old bean" and who have fun, all in a good cause. Their boss, the mysterious Mr Carter may call Tuppence "little lady" but she's a thoroughly emancipated woman, while Tommy reads the Daily Mail and actually applauds the good bits. SIGH. He's not all awful, though. Christie gifts him with a fine line in wit. He greets a grubby villain with "Someone's not been using Pears soap," and bubbles merrily along - in later books he becomes much smarter, but here he's like a lump of wood with manners.

There's a contrast between two American lovers, who are sprightly and open-hearted, and Tommy and Tuppence, who very awkwardly declare their love on the final page ("They sat very straight and forbore to look at each other").

The actual plot is merry enough, and instantly familiar to readers of "Why Didn't They Ask Evans?", only better. Why that isn't a Tommy and Tuppence book is baffling, although perhaps her readers would have cried foul, as so many of the tropes (mental homes and clifftops and photographs and mysterious impostors) reoccur in that book. This is like a template for much later Christie - we even see elements of it spoofed in The Seven Dials mystery.

Sadly, this familiarity breeds an early suspicion. If you've read a lot of Christie recently you'll start twiddling your thumbs fairly early on. How was Marguerite murdered without any of Tommy and Tuppence's band of friends noticing? How does Mr Brown keep discovering their whereabouts when only the four of them know? How, tell us, how? It's a technique that Christie perfects in later books, but here the reader will have spotted a good hundred pages before our heroes do that All Is Not Right in their camp.

But this is a minor flaw - this is really a magnificent early work, breezing along with an almost improvisational joy at the twists and turns of the narrative. It's also refreshingly naive - a lot of elements are just woven in from John Buchan and Sapper without the later filtering and caution that Christie exhibits (Mr Brown is very like the multi-faced villain of 39 Steps). An exception is Tuppence's lovely relationship with Albert, the page boy addicted to pulp crime - and, as we'll see when we hit Partners In Crime, the next time we meet Tommy and Tuppence they've become a smarter vehicle for literary pastische. But hooray old thing.

It may not be

By the Pricking of My Thumbs (1968)

Plot: An old lady goes missing from a retirement home and it's all to do with a mysterious picture.

Well, we're not meeting Tommy and Tuppence in order. Christie's sleuths don't generally tend to change that much, but Tommy and Tuppence are the exception, growing older each time we encounter them. We first meet them just after the First World War and here they're all grown up - although clearly not quite in their 60s.

This is another nostalgia murder, with a clue to a long-forgotten crime and the title being a quotation from a rhyme (well, okay, Macbeth, so it's not quite a nursery rhyme, but it fits interestingly in with other rhyming titles). As Tommy and Tuppence have aged, so has their quarry. As Tuppence puts it, "If you're pretty nasty when you're twenty, and just as nasty when you're forty, and nastier still when you're sixty and a perfect devil by the time you're eighty...", presciently predicting the course of the story before she meets dotty Mrs Lancaster with her question "Was it your poor child?" (a question that apparently will crop up a few times in various books), a red-herring that's vital to the plot of this book.

This is a wild departure from a rigidly plotted Poirot of murder-investigation-revelation. This is more like a teasing quest for something unknown. Is Tuppence looking for inner peace, a missing pensioner or a house in a forgotten painting?

What evolves is a weird first half that should be BORING. Nothing happens. There's a feeling of missed opportunities - Tuppence always turning up too late, or pottering aimlessly around the village where she's staying, always just a few steps away from a mystery. But amid all the small talk and banter, there is a feeling of creeping, creeping menace - of things found in chimneys, mysteries in graveyards, and village gossip no longer repeated. And then BANG! Tuppence goes missing, and it's up to Tommy to rescue his wife.

The second half features corrupt solicitors, a search for clues hidden in a painting, talk of mental homes and a complicated conspiracy being gradually revealed. And it's all rather marvellous. As Tuppence comments when they're re-united "Hearsay, suggestions, legends, gossip. The whole thing is kind of like a bran tub."

But, with careful sifting, the results are suitably rewarding. This is a story that really does pay off. Whereas the nostalgia murder of "Five Little Pigs" is more a clever stylistic exercise, this is a genuine treasure hunt with an obvious prize, a suitably horrible mystery, and everything to reward the reader from secret rooms to fiendish clues.

This is really Tuppence's book. She's a breath of fresh air after the omnipotence and self-confidence of Poirot and Marple. She's just clever, intuitive and genuinely interested in human nature, while at the same time worried that life has passed her by. She gets into terrible scrapes that you wouldn't imagine happening to Marple, and her detecting is methodical, almost plodding, in a way that would have Poirot despairing. And yet... she is immensely lovable because of it.

NEXT: Miss Marple gets A Pocket Full Of Rye