This book is… strange. I know, right? Frank Herbert, the guy who gave us the Dune universe, wrote a strange book? Who would have thought?

In some ways, of course, it’s more grounded in reality than Dune. It’s set on Earth, albeit at some point in the (then) future, when there is a war for oil being fought between Eastern and Western powers. There’s no spice, no sandworms, no telepathic witches, no psychedelic twists on Middle Eastern religions.

But this relative normality makes the remaining weirdness really, really weird. There are only four major characters, all of whom are members of a submarine crew on a mission to find a deep sea oil well while avoiding detection by the enemy. One of them is newly assigned, and his job is to analyze the psychology of the other crewmen.

Also, because of a sabotage incident early on, it’s clear to all four men that at least one of them is a spy. No one can completely trust anyone else, and at different points, each man does something that brings him under suspicion.

Add to this the intense psychological pressure of isolation deep underwater during an interminable war, and everyone begins to lose their minds to greater or lesser extents. Even the psychologist, steeped in Freudian and Jungian theory, begins to lose his grip on sanity. Or what he thinks of as sanity, anyway. For what the book ultimately asks is, what does sanity even mean in such an insane situation?

At the beginning of the book, I hated it. Herbert’s penchant for writing the characters thoughts in italicized bits of exposition, which will be familiar to readers of Dune, is out in force here, and it annoyed me at first. But gradually I got into the swing of it, and after a while, I was hooked. It turns slowly into a fascinating philosophical and psychological drama, and by the end, I felt like I had just read something every bit as thought-provoking as Dune, but way tighter and more concentrated.

There are some very memorable lines in this book. Like this:

“There are men all through the service–not just the subs–who are so sick of war–year after year after year after year of war–so sick of living with fear constantly that almost anything else is preferable. Death? He’s an old friend–a neighbor just beyond the bulkhead there.”

And this:

“Each of us is the enemy”–Bonnett’s voice grew firmer–“to the other and to himself. That’s what I mean: I’m the enemy within myself. Unless I master that enemy, I always lose.”

To be fair, there is also some semi-incomprehensible jargon:

“Johnny, do you feel hot enough on the remotes to snag our ballast hose in the fin prongs of one of our Con-5 fish?”

This book is very light on description. Herbert basically expects the reader to fill in a lot of the details for themselves. Which, I have to say, I liked. Not to say that I wasn’t confused at times about what was actually happening, because I was, but at the same time, I appreciated that Herbert was like, “Look, there’s a war on, and these guys are in a submarine. Use your imagination if you want to know what everything looked like!”

This book isn’t for everyone. Some people may find it boring or confusing or just too bizarre. But if you like intense psychological drama and meticulously crafted characters, you’re going to love it.