As a crime novelist, Benjamin Black is a mischievous man. Everything in this book is just as it seems — if only we could be sure what that seemed to be.

The import-export firm of Delahaye & Clancy of Dublin is owned by two prominent families. Although they do not particularly like each other, they have vacationed together for a month every summer for years. It is there we begin, as the overbearing Victor Delahaye invites the awkwardly submissive son of his partner Jack Clancy out for a sail, then commits a ghastly suicide which strands the young man, who is terrified of water and clueless about sailing, to fry in the sun becalmed at sea.

If this isn’t jarring enough, Jack Clancy himself soon becomes the victim of a mugging and then a drowning, a probable murder. That makes for two funerals at which family members do very little genuine grieving. “The dead get so much more than their share of praise,” one character muses to herself, “and all just for being dead.” Followed by, “Come now, Maggie dear, don’t upset yourself so — think of your asthma.”

These matters are investigated — if that’s what you can call the casual and unconventional techniques of Detective Inspector Hackett and his colleague of happenstance, pathologist Dr. Quirke. Quirke seems most aptly named.

We meet the victims’ family members. Just when you consider diagramming the family trees to be sure you have all the relatives straight, Black adds new characters that don’t fit. Only a couple are minor characters, one of them named, well, Minor. But how minor can they be, really, especially when one keeps getting mentioned and the other keeps showing up?

And there is a lot of sex. A lot! These people enjoy very little impulse control, yet we can’t be at all sure how good it was for any of them.

The characters are deftly drawn, the descriptions taut and dense. You’ll want to linger over them. As a matter of fact, you will need to since the plot advances chiefly by silences and interior monologues rampant on fields of doubt. Wait, did we read that right? All the clues are right there on the pages, Dear Reader. Didn’t you catch them the first time?

Black has written several Hackett-Quirke mysteries. He has been even more prolific under his real name, John Banville, whose 18th novel, The Sea, won the Man Booker Prize winner in 2005. He is a very fine writer. Things do not happen to his characters. His characters cause them. And deserve them.

I have one critical issue with Mr. Black. This book shouldn’t end. That is a gripe, not a compliment. Without naming names or disclosing more than you should know, the book portends a third death at sea — a palpable maybe — and some characters simply fade away. For a detective-based murder mystery, this is an unsettling conclusion. But then, I did warn you. Benjamin Black is a mischievous man.

Some incautious people may pick up Vengeance for a beach read, but don’t you do it! You must savor the writing. There are no idle moments. Best to hold this one until the summer ends, until you are back at your fireside, the world outside in a slumber lulled by a distant sea, a dollop of Jameson in your glass.

Tom Phillips is a retired corporate attorney who lives in Chicago, grumbles a lot about national politics and admits to enjoying escapist fiction.