As always, I encourage you to read the books in this series in the order of the chronology they describe rather than by publication date. Mr. Cornwell has come back again and again to "fill in" between books with other books. You'll enjoy the series more in a logical order.
At the current time, this is the 14th book in the chronological series.
After the desperate battles to throw the French out of Portugal and to enter Spain by breaching two fortresses, the British and their Portuguese and Spanish allies are near Salamanca looking to set up a battle that they can win decisively against the larger French forces.
As the book opens, the dangerous French Colonel Laroux has extracted some important information about a British spy ring through torture. But he's made a mistake and taken too long. He's at risk to be captured. Being a capable dissembler, Laroux soon has most of the British fooled . . . but not Sharpe. Laroux soon shows his true colors and the British realize it's essential that they contain Laroux's information before their spies are killed.
In the process, Sharpe becomes fascinated by Laroux's sword and begins to wish it were his. You'll begin to wonder how that might occur.
Next, Wellington has the relatively simple task of seizing three forts against far from extreme opposition after the main French army retreats. But it proves to be more difficult than expected. Someone has tipped off the French about when and where the attack will come.
Sharpe meanwhile is drawn into the party life of the Spanish aristocracy, finding himself drawn to the alluring La Marquesa despite being a newly married man. Is she also interested?
Sharpe is now asked to solely focus on Laroux, and a fascinating sequence of unexpected events ensues.
In the second half of the book, you'll find many more surprises than most Sharpe novels contain. As the historical note at the end indicates, many of these surprises follow the facts of the real history pretty closely. Within that framework, Mr. Cornwell has added his magic touch to weave some imaginary plots involving fictional characters that work seamlessly together. It's very nice!
Although the battle writing cannot be nearly as engaging as usual because the nature of the battles here provide a less interesting factual basis for the descriptions, there are still some pretty neat touches in giving us a sense of how Wellington won the day against the crafty and determined marshal Marmont.