In January 1944, Helmuth Von Moltke, a founding member of the Kreisau Circle, one of the leading resistance groups against the Nazi regime, was arrested by the Gestapo. Following internment at Ravensbrück concentration camp, he was transferred to Tegel prison in Berlin. Shortly after his arrival he was charged with high treason — a crime punishable by death.

Although no one could save the condemned man, the prison chaplain — a friend and fellow member of the Kreisau Circle — was able to enrich his remaining months. He put his life on the line by smuggling the clandestine correspondence between Helmuth and his wife, Freya, in and out of Tegel. Freya then hid the letters in the beehives of the family's estate. Helmuth was executed in January 1945 but Freya survived the war and lived on. In accordance with her wishes, their letters were only made available to the public after her death in 2010. Published to considerable acclaim in Germany a year later, they now appear in English, translated by Shelley Frisch.

"Last Letters" is both a remarkable historical document and a powerful testament of imperishable love and unwavering devotion. That heartfelt emotion is there right from the start. In Freya's first letter to Helmuth, dated Sept. 29, 1944, she muses on the years they spent together and what little time they have left. He, she claims, will die for something worth dying for. She will soldier on with her two little sons.

"I will have to go on living," she writes, "and that will be hard, but it will work out, because I will be able to go on loving you."

If this reads like the final letter rather than the first one it is because neither Helmuth nor Freya knew when the gallows would beckon. "I regard every letter I now write as the last one," Helmuth tells her. Although the shadow of death looms over their correspondence, both parties remain stoic. For Helmuth, death is merely "a peripheral process." He focuses instead on more important topics: his health, his children, his day-to-day ordeals ("we are now shackled day and night") and the work he is doing on his defense for his imminent trial. Freya reports on home life and her ongoing efforts to secure a petition for clemency.

Each is bolstered by the other, and by their faith in God. However, as the months tick by, cracks appear in their defenses. In one letter, Helmuth describes a long day's journey into the darkest of nights. In a letter from Freya, written 10 days before her husband's death, she relays her own moment of crisis. Frisch's translation skillfully conveys the couple's range of emotions. Despair should dominate but it is ultimately trumped by "something far more beautiful and enduring, for which there are no proper words, something we possess as a precious treasure, and will never have to lose, and never will lose."

Malcolm Forbes has written for the Times Literary Supplement, the Economist and the New Republic. He lives in Edinburgh, Scotland.

Last Letters: The Prison Correspondence 1944-1945
By: Freya and Helmuth James Von Moltke, translated from the German by Shelley Frisch.
Publisher: New York Review Books, 392 pages, $18.95.