It would take a series of spoilers to explain who might have killed whom in “The Galapagos Affair.” See the movie and find out, and revel in the grim gallows humor.

Some of the cast of characters in “The Galapagos Affair.”

By Gerald Peary

How very odd to have a two-hour documentary about the Galapagos Islands in which the name of Charles Darwin isn’t mentioned once. Here we are, at the epicenter of Darwin’s God-shattering theory of evolution! The materialists’ Mecca! But that’s not why the European protagonists of Danya Goldfine’s and Dan Gellers’s arresting, one-of-a-kind The Galapagos Affair: Satan Came to Eden (at the Kendall Square Cinema in Cambridge, MA) ventured there, because they were interested in scientific research, or because of the extraordinary rare and varied bird and animal life. Had they ever read Darwin’s Voyage of the Beagle? Did they even notice the stone-age lizards and giant tortoises basking in the sun?

They emigrated to the Galapagos because they wanted complete solitude, because they wanted to test to the limits their self-reliance and self-sufficiency. In truth, they might have chosen an island anywhere, as long as it was short on people. But the Galapagos it was. They knew of one Galapagos Island, Santa Cruz, which had a bit of scattered human population. That was a spot to shirk. Instead, starting in 1931, the principles of The Galapagos Affair became the first two-legged inhabitants of the isolated island of Floreana. At first there were two people, then three more, than another three, than additional children. A utopia? Hah! There were fierce animosities, some kinky sexuality and, by mid-1934, one person was dead, perhaps poisoned, and two others had disappeared, almost certainly homicides. And then another disappeared. As the subtitle says, Satan Came to Eden.

In 1998, the two future filmmakers (they also co-directed Ballets Russes) arrived in Santa Cruz as part of a movie crew doing a nature documentary. They felt, they’ve said in interviews, the awe of being in the Galapagos. And they were transfixed by the lurid story of what happened there in the early 1930s, part of the local lore. Here was the basis for a thrilling documentary. But what records remained from eighty years ago? Incredibly, there was a whole media trail. Newspapers around the world had offered seedy tabloid stories of the Edenic experiment, and there was even more press when Floreana exploded with missing and dying persons. Additionally, some of the Floreanans kept vivid diaries, and several of these were converted later into published memoirs.

Goldfine and Geller could use the media coverage for spicy graphics, and the diaries and memoirs became the texts for the voiceover, spoken by actors (including Cate Blanchett) representing the denizens of Floreana. A good start for the duo of documentarians. And then came a remarkable break. They became privy to a private collection of 16mm film which had been contributed to the University of Southern California. This is what we get on screen: actual footage of all the people who lived on Floreana, taken by touristic visitors. And even more: a trashy, kitschy, love melodrama shot on the island, featuring Floreana’s most flamboyant citizen, the Baroness Eloise von Wagner.

So: full steam ahead for The Galapagos Affair: a surprisingly brisk two hours recreating days and nights in Floreana, 1931-1934.

It all began with Floreana’s Adam and Eve, Dore Strauch and Dr. Friedrich Ritter. It wasn’t the rise of the Nazi party which led them to flee Germany but the dreary bourgeois life there. They shed a husband and wife, respectively, and sailed to the Galapagos by way of Ecuador. Ritter was “my teacher, my guide, my fate,” according to the diary of the lovestruck Strauch. But he was far less sentimental. “To live is to suffer” was his credo, the words of his hero, Nietzsche. They embarked at Floreana to work, work, work, and work some more. “Paradise, you must create it,” insisted Ritter. “There is no place of rest, or contemplation,” Strauch complained in a letter. ”Nothing but discipline.”

Still, they wanted to be alone, and were horrified when three more Germans encamped at Floreana: Heinz Wittmer, Margret Wittmer, and Harry, their sickly son. The Wittmers moved into a set of caves above Strauch and Ritter, and they waited for some hospitality from the original settlers. And waited. But Dr. Ritter was a misanthrope to the bone, and Strauch felt that the Wittmers were exactly the drab middle-class people for whom they’d left Germany.

But the Wittmers were a piece of cake next to the final invaders of Floreana. They were the ditsy, bra-less Baroness von Wagner and her two lovers, Robert Philippson and Rudolf Lorenz. They built a camp halfway between the others, forming a passionate ménage a trois in which Lorenz was the odd man out. Bullied and beat up, he would arrive at the Wittmers’ domicile for some kindness, before returning obsessively to the lair for more bad times. Meanwhile, the Baroness was plotting her grand plan, anathema to the Wittmers and Strauch and Ritter. She would build a hacienda hotel, and bring tourists to Floreana.

Everyone loathed everyone else. Except for that one day. A child was born to Margaret Wittmer, and Dr. Ritter finally was prodded to help with the birth. All on Floreana celebrated the new baby. One diarist described it as “Christmas.”

But soon after: mayhem and death. It would take a series of spoilers to explain who might have killed whom. See the movie and find out, and revel in the grim gallows humor.

In 1998, Goldfine and Geller actually met on the Galapagos the last of the original group, a crusty old woman in her 90s who didn’t want to talk with them. A possible murderer. The survivor of the fittest.

Gerald Peary is a professor at Suffolk University, Boston, curator of the Boston University Cinematheque, and the general editor of the “Conversations with Filmmakers” series from the University Press of Mississippi. A critic for the late Boston Phoenix, he is the author of 9 books on cinema, writer-director of the documentary For the Love of Movies: the Story of American Film Criticism, and a featured actor in the 2013 independent narrative Computer Chess.