Simon doesn't want to let go.

I'd been planning to work on another book set in the American revolution, and probably still will. I've heard authors say that their characters come to life and to a certain extent dictate what you do. Never really believed it. My mistake.

Simon and Katherine don't want me to take a break. As I try to work out the plot line for the new book, they sneak in, unbidden and demand attention. Without really trying I'm further on a plot line for a third book with them, than I am on the new one.

It would start after the first and cover their wedding and posting to Vienna.

1. Wedding in St. Osyth. They've been convinced to post the banns rather than use the special license Wolfe brought. This means that their family has a chance to gather. This allows a few discussions and family secrets to emerge.
2. Back to London. While getting ready to be posted there are things to do. They might connect with Freddy (the banker who is worried about cloth sales to 'Denmark') and Katherine can get into some sort of trouble. Maybe do something with her friends that is subject to misinterpretation.
3. Cambridge. Simon has to learn how to use codes, ciphers, secret inks and various 18th-19th century tradecraft. Sounds like I'm channeling LeCarre here, doesn't it? They did use surprisingly sophisticated techniques so he'd need to learn them. Gives me a chance to catch up with a couple of loose ends.
4. On Clarke's ship. He's posted to the Mediterranean fleet. I'll have to do some research for this. The little bit the navy appears in Katherine's choice didn't require much because it wasn't very long.  (I did have to research the shipyards, though).
5. ???

They have to pick up a romantic interest somewhere. In the French Orphan it was originally going to be Sally and Wilcox, but that didn't work out. O'Reilly sort of grew on me, and her. I wonder who it will be this time?