I don't remember where I picked this one up, but it's the second of two books about Paul Crane, a free-lance engineer who, in the first book, Red Heroin, is coerced into working for the CIA under the threat of going to prison if he refuses. In this one, he's been out of work for a while. The CIA offers payment if he'll work for them again, and though he's still a very reluctant spy, he agrees to pose as a traitor who has the plans for some new laser technology that he's willing to sell to the Chinese. As you might expect, to make his cover secure, the FBI is kept in the dark about things, so they're out to stop Crane any way they can.
There's quite a bit about about sailing in the book, so if you like that sort of thing, you'll get plenty of it. To me it started to seem like padding after a while, but Curtis/Pournelle makes up for it at the end with some really nice chase/pursuit sequences in an experimental plane.
This was a sort of middling book for me. It's okay, and Crane's all right as a character, but there's nothing to make it stand out. It's just as well the Pournelle gave up on spy fiction and turned his hand to SF. He's done a lot better work in that field. I'd recommend this only as a curiosity, and cheap copies can be found easily on the Internet.