If you're looking for an even-handed recounting and reflections on this book, you should probably check out Jeffrey Keeten's stellar review (it has lots of pictures and everything). However, if you're looking for my favorite moments of skullduggery (along with the occasional pop culture parallel), then you're in the right spot.
Eddie Chapman (codename: ZigZag) was, among other things, the head of the "Jelly Gang" (they used gelignite to break into safes), a bit of a lady's man living in "the world of pimps and racecourse touts, pickpockets and con artists; late nights at Smokey Joe's and early champagne breakfasts at Quaglino's." Much like my personal favorite and the world's greatest secret agent (albeit fictional), Sterling Archer (codename: Duchess), Eddie's silver tongue had a way of getting him out of quagmires and back into the good graces of those who he'd wronged in the past.
Unfortunately, the jig was up, and he landed himself in jail on Jersey Island (almost as bad as being imprisoned on the Jersey Shore, but with far less hair gel and fake tanning cream). I'll skip a lot of important information here and just tell you he ends up being recruited/courted as an agent for the Abwehr (one of those dastardly Nazi intelligence agencies). As a smooth-talking con man who has exhibited few moral compunctions even as a thief, he was a pretty great candidate to become a British spy (but for the Germans- so German spy?). I mean everyone knows that, as a spy:
So he luftwaffles or 99 red luftbaloons himself into Britain where he, promptly, double crosses (or triple crosses- it's hard to follow) as he cozies up with MI-5 and has to deal with quite a crew, including Robin "TinEye" Stephens who rocks a monocle like nobody's business. As well as Jasper Maskelyne, a magician in the employ of MI-5 who helps them engineer an illusion (yes, they actually do refer to it as such, so Gob Bluth can rest easy) to make it look like ZigZag is carrying out his subterfuge as promised to his Nazi pals.
The thing about Eddie Chapman was that he basically thrived in the worst of circumstances. He liked to keep things loose and (another shoutout to Archer) couldn't necessarily be relied upon to keep his mouth shut when it came to being a secret agent, especially when ladies were involved. Really, he was kind of a loose canon- unless, of course, he wasn't. That's the thing about being a great double agent, it has to be hard for people to get a pulse on you. That being said, it was probably a good call on the part of MI-5 to try to sever ties. That being said, his life made one heck of an interesting story.