"Michael Innes" was the pseudonym under which J. I. M. Stewart wrote nearly fifty detective novels between 1936 and 1986.
His works contain the following tropes:
- Action Girl: Sheila Grant in "The Secret Vanguard" is forced to become one in fairly short order.
- Amplified Animal Aptitude: In "The Daffodil Affair", the title character is a horse that, like Clever Hans, can apparently recognise numbers.
- Big Fancy House: Nesfield Court in "The Weight of the Evidence"; the description is at pains to point out how vast and sprawling it is, and it takes Appleby several attempts to find which of the entrances is the one actually in use.
- Confronting Your Imposter: How Philip Ploss in "The Secret Vanguard" met his end. He was a minor poet who overheard two spies exchanging information disguised as a poem. One claimed it was by Ploss; the real Ploss pointed out that it wasn't, and got murdered for his pains.
- Decoy Protagonist / Genre Shift: "The Secret Vanguard" opens as a conventional detective novel might: the first chapter introduces the murder victim, and the second and third have Inspector Appleby beginning his investigation. Then the point of view switches to Sheila Grant, who unwittingly stumbles across a Nazi spy network, and for most of the rest of the book she's the protagonist of a spy thriller.
- Evil Gloating: One of the spies in "The Secret Vanguard" tries this on Sheila. Unfortunately for him, she's got a pistol and is prepared to use it.
- Fauxreigner: In "The Daffodil Affair," Appleby and Hudspith play up their cover story as hard-drinking Australian wool-traders for all they're worth.
- Free-Range Children: In Operation Pax / The Paper Thunderbolt, shoals of them, bicycling through rural Oxfordshire, play a significant part.
- Genre Savvy: Sheila in "The Secret Vanguard". Knowing she's being pursued by a spy ring, she's well aware of what it means when she's asked "Have You Told Anyone Else?", and quickly changes her answer from "No" to "Yes", giving her enough time to escape.
- Haunted House: One gets stolen (dismantled over the course of a few days and reassembled elsewhere) in "The Daffodil Affair". People took a while to realise, because this was in London during the Blitz and the initial assumption was that it had been destroyed by a bomb.
- I Know You Know I Know: In "The Daffodil Affair", Appleby and Hudspith are undercover policemen posing as Australians. The Big Bad knows they're policemen, but is letting them think that he doesn't know. What he doesn't know is that Appleby and Hudspith know he knows.
- Lazy Bum: Lasscock in "The Weight of the Evidence", an academic who's invariably to be found lounging in a deckchair rather than doing any work. His tendency to come down with a 'slight chill' is a running joke among his colleagues.
- Leaning on the Fourth Wall:
At this point, she thought, the instalment should end. Will the heroine get away? Come next week and see.
- At the end of a chapter in "The Secret Vanguard", Sheila steals a motor-boat and escapes from the Nazis' headquarters:
Hudspith: We're in a sort of hodgepodge of fantasy and harum-scarum adventure that isn't a proper detective story at all. We might be by Michael Innes.
- In "The Daffodil Affair":
Appleby: Innes? I've never heard of him.
- Path of Inspiration: The Big Bad's plan in "The Daffodil Affair" is to create one.
- The Prankster: Professor Pluckrose, the victim in "The Weight of the Evidence", plays spiteful tricks on his fellow academics. As Appleby finds, that gave a lot of people a motive to drop a meteorite on his head.
- Split Personality: Lucy Rideout in "The Daffodil Affair" has three personalities: Young Lucy, Sick Lucy and Real Lucy. Appleby kills the first two with carefully-chosen words, leaving Real Lucy in sole possession.
- Spy Speak:
- In "From London Far" the main character absently quoted a line or two of verse in a tobacconist's. When the clerk gave him a funny look he said simply "London: a Poem." and the clerk, who thought he'd said "London's goin'," replied "Rotterdam's gone" and allowed him entry to what turned out to be a base of operations for some rather high-class art smugglers/thieves.
- In "The Secret Vanguard" the spies communicate by quoting poems, into which they slip extra verses containing the necessary information.
- Stern Chase: The bulk of "The Secret Vanguard" involves Sheila Grant being pursued through the lonelier parts of Scotland by Nazi spies.
- Tap on the Head: In "Death at the President's Lodging", Inspector Appleby is knocked out by a blow to the head. One of the suspects, an author of detective novels, points out how dangerous it could have been.