Ha'penny occurs just a couple weeks after Farthing, once again alternating chapters between our female protagonist and Officer Carmichael. This time, the female protagonist is one of six sisters with very different ideas and beliefs. One of her sisters is the wife of Himmler and one is a communist. Viola, however, is an actress which her family considers worse than the others.
The story starts with a bomb explosion that kills one of the other actresses in Hamlet where Viola has agreed to play Hamlet (crosscasting was popular). Viola gets gradually pulled into the plot to kill Hitler, Himmler, PM Normanby, and her sister, while Carmichael gradually figures out what happened and why there was a bomb. Carmichael is not only under the thumb of the government because they know he's gay, they want him to head a new department. The Watch will be like the Gestapo and since they would kill him if he refused, he hopes he'll at least be in the position to look the other way sometimes.
It's a great mystery plot, but this book is clearly using the Nazis and the British acceptance in the alternate world to model Bush's response to terrorists. It's a compelling read and everybody should read the series.