This is book four in this series so, to get the very best from it with regard to character backstory and development, you would be better off starting from book one and reading in order.
So, Jenny is trying to persuade John to learn to sail. But his first foray into this new pursuit ends in tragedy as a body is found. This means he has to swap his sailing hat for his professional one, that of DI John Tanner, and dive not into the water but into the investigation of a crime that is more historic in nature. Stakes get higher and Jenny gets more personally involved leaving him to worry about her rather than concentrate on the case in hand. With the body count rising, can he cut through all the noise and work out what in the heck is going on, who is doing it, and why? And more importantly, bring justice...
I respect that some may not but I actually love the bickering between Jenny and John. It might be a bit implausible that they are still working together but, heck, this is fiction and it's a bit of fun and light relief along the way when dealing with the most heinous crimes that this author thinks up for them!
As with the rest of the books in this series, the Norfolk Broads itself plays a major part in what is going on, probably more than the previous books and I did learn quite a bit more about that world. All is explained for the layman and complements rather than distracting from the action going on with the case in hand. The action hit the ground running and didn't let up until right at the end, with a cracking finale that had me nearly reading from behind a cushion. Well, I kinda care about the characters...! Pacing is good and, as usual, there is no superfluous waffle to distract the reader.
All in all, a cracking addition to what is shaping up to be a high quality series of books.