I was first drawn to Knights of the Sea by the hilarious cover art. Now, having read the book, I can say two things: First, the art is accurate! Every element of the cover design -- wolf, capsized boat, ghostly damsel, and lemon -- is present in the plot. Second, the book is just as funny as the cover, and in a very good way.
In the previous THE WELLBORN CONSPIRACY book, Sporeville, Elliott Graven made a powerful enemy in the dastardly Professor Strange. As Knights of the Sea begins, he survives a murder attempt by one of Strange's henchmen. He then arrives for a visit with his lycanthropic sweetheart, Paisley, hoping for a peaceful and idyllic summer to take his mind off mortal danger for a while. Instead, he finds that Paisley is smitten by a dashing German submarine builder and that yet another deadly plot is in the works.
Knights of the Sea begins with a brief summary of Sporeville, which serves two purposes: it's funny, and it infodumps-without-infodumping, bringing readers up to speed on previous events without interrupting the story proper to do so. This is followed by a Dramatis Personae. This too is humorous, and provides a handy reference when the large cast becomes a little unwieldy to hold in one's brain.
The drily hilarious tone continues throughout the novel. As an example, in the following passage Elliott is trying to decide how to introduce himself to a new acquaintance:
""Mrs Anna Leonowens. I am organizing the new Victoria School of Arts."
Too late, Elliott realized he would be expected to introduce himself, now. His mind went blank. In its dark, aching recesses, only ridiculous false names appeared. Nemo Jimmerson. No. Montagu.... Van Buren. No, that would be as bad as using his real name. Desperately, he smiled and scanned the Chronicle. The smile seemed to worry Mrs Leonowens.
His eye alighted on `William Fielding.' That sounded like a real name. Of course, it probably was. It was in the paper. Wait. No. Impersonating the premier might only make matters worse. Especially as Fielding wasn't very popular at the moment, having failed to fulfil his election promise of seceding from the country."
Paul Marlowe's style of humor is reminiscent of Neil Gaiman's lighter works. When Elliott finds himself getting inadvertently drunk, it's easy to imagine that Benjamin Lassiter is sitting a few barstools down, ordering a ploughman's, and that in that corner over there, Crowley would be taunting Aziraphale with the dearth of good movies in Heaven, had movies been more fully invented at the time.
If you enjoy dry wit, Victoriana/steampunk elements, and plucky teenagers saving the world, you'll probably like Knights of the Sea. It's an tale of high adventure that takes a humorous look at... well, pretty much everything, from politics to romance to lycanthropy. Give it a shot if you liked Stardust (Paperback) or Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch.