A poor widow visits a hospital for disabled children. She has brought fruit bread for the medical director and biscuits for her epileptic son, who is being treated there. It’s been nearly a year since her child was taken away and hospitalized. “Couldn’t I see him now, just for a moment?” she begs. The director refuses. “It’s the regulations, I’m afraid, Frau Pabst.”

The year is 1941. The country, Germany. What Frau Pabst doesn’t know—what the director can’t bring himself to tell her—is that her son is dead. He was killed as part of Aktion T4, the Third Reich’s program of involuntary euthanasia targeting “lives unworthy of life,” in the Nazis’ phrase.

This nearly unbearable scene appears in “All Our Children,” a drama showing at the Jermyn Street Theatre in London’s West End. The setting, plot and most of the characters are fictional. But the historical background is factual. “All Our Children” presents a gripping theatrical account of the Nazis’ project to liquidate the disabled—and one Catholic prelate’s struggle to thwart it.

This prelate is the play’s only real-life character. At the zenith of Hitler’s power, Clemens August Graf von Galen used his pulpit as the bishop of Münster to rail against Nazi dictatorship, earning him the moniker “Lion of Münster.”

Galen, born into an aristocratic family, initially made peace with National Socialism. He saw it as an antidote to the humiliation of Versailles and the moral decay of Weimar. He was quickly disillusioned. Nazism was a dangerous “pagan” ideology, he wrote in a 1934 pastoral letter. The bishop’s ecclesial stature and moral gravitas made him difficult to silence.