Chris Nicola did an astonishing thing. The New Yorker and amateur spelunker went to Ukraine soon after the Soviet Union collapsed, looking to explore both his Eastern Orthodox heritage and the gypsum caves of the region. He found an incredible story of Jewish heritage that involved the caves whose interiors rarely had been seen by human eyes.

Underground, he stumbled over the remains of stoves and furniture and, finally, a woman's shoe. He couldn't imagine why a woman would have been that far below ground, so he went digging in the towns above. At first, no one would talk -- the citizens of the newly independent country weren't yet prepared to speak to Westerners. But, as Nicola says, "I'm very outgoing," and he kept trying for years, when he finally heard: "Maybe some Jews lived in the cave."

This stunning story is told in the documentary "No Place on Earth." Nicola eventually found survivors who had actually lived in the Vertebra and Priest's Grotto caves for a year and a half during World War II. The film's marketing department bills this as "the longest underground survival in recorded human history." It recalls Agnieszka Holland's 2011 feature film "In Darkness," which dramatized the story of a Polish Catholic sewer maintenance man who helped Polish Jews survive in the sewers of Lvov. There are re-enactments here, but the best parts of Janet Tobias' documentary are the interviews with the real survivors, who lived in the caves as children and, luckily, lived to tell the tale.

On screen
'No Place on Earth'
» Rating: 3 out of 4 stars
» Starring: Chris Nicola, Saul Stermer, Sam Stermer, Sonia Dodyk
» Director: Janet Tobias
» Rated: PG-13 for thematic elements including brief violent images
» Running time: 83 minutes

It was matriarch Esther Stermer who had the foresight to prepare her family for the "black clouds" she saw coming. She heard in 1938 that Canada was accepting immigrants. Her family was approved, but war broke out exactly one week before their boat was to leave. Esther refused to take orders to move to the ghetto the Nazis created. She first had her older sons build bunkers, where they got by until 1942. Then she realized the situation was deadly and instructed her children to find a place in the forest that would house them. They ended up living underground with some other Jewish families.

"I would make-believe I was living in a castle. It was wonderful not being in the bunker," recalls Esther's granddaughter Sonia Dodyk. That's about the best they could say about the situation. One man remembers being a boy so thirsty he was willing to risk death by going above ground for a drink. "Sam says he could see. Maybe his eyes were different," Saul Stermer says of his cousin, speaking about living in a pitch-black environment for so long.

Sometimes it feels as if the doc brings up more questions than it answers. That's certainly true of the family situation. But what it does have to say is well worth watching. The family managed to bribe officials for their freedom, but the group eventually had to change caves. Though she's a living presence in the documentary, it's Esther Stermer who makes the deepest impression. "When you came to visit Grandmother Esther. ... It wasn't playtime," Sonia reports. "She was a businesswoman," whose smarts saved the lives of a few dozen people.

But it's the explorer who best expresses the heart of the story. "Back in what we like to call prehistoric times, people escaped beasts by hiding in caves," he explains early in the film. Some things, unfortunately, never seem to change.