Digging deep into the secrets of Titanic's demise in "Last Secrets"

The secrets in the title of Brad Matsen's new book are those of greed and deceit — "Titanic's Last Secrets" concludes that owners and builders of the ocean liner Titanic made decisions that saved them huge amounts of money and sacrificed more than 1,500 lives.

"Titanic's Last Secrets: the Further Adventures of Shadow Divers John Chatterton and Richie Kohler" (Twelve, 322 pp., $27.99) is a tribute to the passion and obsession of those Matsen calls "Titaniacs," who devote their lives to increasing the world's sum of knowledge about the sinking of the world's greatest luxury ship.

There are thousands worldwide who believe, reasonably or wildly, that they know something about the Titanic no one else knows. Matsen concentrates on the actions of a dozen or so who actually do know the subject better than anyone else.

He details the life-risking work of divers John Chatterton and Richie Kohler and a self-educated naval architect, Roger Long, in their search for one more piece of evidence to settle some hotly controversial speculation: that the owners, builders and designers skimped on the construction of the Titanic and her two sister ships; that their cut-rate design led the ship to sink so fast that only a third of the passengers and crew could be rescued; that they knew what had gone wrong and covered it up. (Chatterton and Kohler were also the subjects of Robert Kurson's best-selling 2004 book, "Shadow Divers.")

Matsen's fast read is divided into three sections: The first and third deal with the search by Chatterton, Kohler and Long and the roller-coaster emotions that accompany their gamble. The middle and meatiest section reconstructs the lives and passions of those celebrated early-20th-century industrialists who built the world's three largest ocean liners, all disgracefully opulent, all doomed.

The Olympic, the precedent-shattering luxury ship that served as the pattern for the other two, collided with a British navy ship on its first voyage, and had to be rebuilt. The second, Titanic, suffered the disaster that became part of America and England's tragic folklore. Matsen offers a heartbreaking, moment-by-moment reconstruction of Titanic's collision with an iceberg on April 14, 1912, and its astonishingly rapid sinking, before rescue ships could arrive.

The third of its class, Brittanic, was converted to a hospital ship in World War I, struck a mine off the shores of Greece and Turkey and sank. It was Brittanic that gave up Titanic's awful secrets. In dangerous dives into the wreck, the explorers were able to discover changes the shipbuilders made in the hull of Britannic after the Titanic disaster. Its builders knew what had gone wrong with the Titanic and tried to correct it in the other two ships, while keeping it from the rest of the world.

An unlikely hero of this oceanic detective story is the archivist of Harland and Wolff, the once-colossal Belfast company that built the three famous ships. Tom McCluskie, plagued by illness and bitter over the meager rewards of a lifetime of work for the shipyard, came out of obscurity to provide the explorers with plans, files and letters hidden from public view for nearly a century, revealing that the Titanic was, in Matsen's words, "a deeply flawed testament to hubris and greed that killed 1504 people."

The author acknowledges reconstructing events, conversations and interior monologues that he could not possibly have witnessed. These recreations from public records, diaries, biographies and interviews are offered in plain text, while verbatim conversations (including recorded outbursts from the divers) are set in quotation marks. It's a technique that helps believability without losing drama.

Matsen's a Vashon Island resident who melds adventure writing with engineering and science. In "Titanic's Last Secrets," even the engineering becomes adventurous.