What do a Jewish woman in Canada and a Christian man in Germany have in common? Secrets.

Toronto-born journalist Martin Himel’s latest film delves into a little-explored corner of World War II: American soldiers who fathered children in Germany, and loved ones whose wartime deaths were never revealed.

These were the secrets kept from Juergen Ulloth of the town of Babenhausen, near Frankfurt, and Malka Rosenbaum of Toronto, explored in Himel’s Secrets of Survival.

Equals parts drama and detective yarn, the documentary takes the viewer on the alternating tales of a man who discovers his father is not the person who raised him, and a woman who finds out that her Holocaust survivor parents had had a sickly baby who was handed to a Gentile family in the forests of war-ravaged Poland.

The discoveries propel both Ulloth and Rosenbaum on truth-seeking odysseys that take them across oceans and force them to confront painful pasts.

The film has its world première April 9 at 9 p.m. on the Documentary channel.

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As far as the bespectacled Juergen Ulloth knew, his father was a veteran of the German navy. Getting married changed Juergen’s life in more ways than one; a town clerk informed him that his surname was not legally Ulloth.

Stunned, he queried his mother, who hinted something was amiss, but would not say more. Her twin sister then told Juergen that his real father was an American GI, something she thought he had always known.

Ulloth, now 70, says the sudden discovery was like having a limb amputated.

Meantime, in Toronto, Rosenbaum, now 64, recalls being a 19-year-old student who was shocked to learn that her parents, both Holocaust survivors, had had another daughter during the war, Esther, who was given to a Christian family for safekeeping and died of typhus.

Rosenbaum hangs onto the hope that it was not her sister who died, but the daughter of the woman who had taken Esther in. Perhaps Esther was still alive.

“It made me question myself,” says Rosenbaum of her new knowledge.

Through letters from his real father to his mother, Ulloth discovers that he is the son of an American soldier named Malcolm William Ingle. His dogged research and correspondence, sheathed in organized plastic pages, take him to Asheville, N.C., and the war grave of Ingle, who died in 1999. It’s a heartbreaking moment, as the normally reserved Ulloth bemoans having missed his “Dad.”

But from there, Ulloth discovers friends who remembered his father, and cousins, who welcome him with southern hospitality.

Rosenbaum’s journey takes her to Israel to consult an aunt, and to Poland, where she meets the family of the woman who had nursed Esther.

It was “unthinkable,” says the nursemaid’s son, not to act.

Rosenbaum receives a measure of closure at the grave of her sister in the town of Staszow, where she lights a candle and recites Kaddish. Esther had indeed died as a baby.

It’s engrossing stuff, but in places  confusingly told. A viewer might be forgiven for believing that the stories of Ulloth and Rosenbaum would intersect; they do not, and, like some of Himel’s earlier films, the whole work might benefit from tighter editing.

Still, it’s a compelling and touching film, one that speaks to the very essence of our personal identities and what happens when those building blocks take a hit.

And in a way, the two stories do meet because both underline how we often fear the truth, or just avoid it. “We were going to tell him,” says Ulloth’s mother in the film. “But I wanted him to grow up with no trouble. It was not right…”

Himel says he was he inspired by the need for survivors to keep the secrets of their survival hidden, and to go on rebuilding their lives.

“I have a special affinity for these stories of lives disrupted by secrecy,” he says in the film’s publicity material. “Inevitably, those secrets catch up with the second generation and have a profound impact on family relationships.”

But “that’s life,” says Ulloth, “and you can’t go back.”