This is the penultimate book in the series of seven Doctor Syn books.
The story is about a sinister new foe Doctor Syn comes across, a dastardly yet dashing and crafty fellow who is trying to marry a wealthy maiden for all of her fortune. To accomplish this he murders her uncle, then sets his sights on further murders and nasty business to get what he wants. Part of his plot directly involves the brilliant Doctor Syn, ex-pirate and current leader of a smuggling ring, but also the parson of Dymchurch-under-the-Wall, a small village in Eastern England. This leads to the villain’s demise of course.
The story is a bit drawn out and at times goes into a lot of unnecessary detail. There is also not a lot of tension as Doctor Syn is always in ultimate control of every situation, he hardly gets into any sticky business which he must brilliantly solve his way out of. But this is what Doctor Syn does in all of the books, so it is nothing new.
Unlike some of the other books this one is not a series of escapades and adventures, it is one consistent story which is good. The best books in the series have been the first two books (the first book though is chronologically the last).
This book was published in 1939, but the book is written more in the style of 18th century English which is fun to read.