This story is taken from an Elizabeth Elliot devotion found on the Back to the Bible website.
The Angel in the Cell by Elisabeth Elliot

My brother Dave Howard does a lot of traveling and comes back with wonderful stories. One summer when the six of us Howards with our spouses got together for a reunion, Dave told us this one, heard from the son of the man in the story.
A man whom we’ll call Ivan, prisoner in an unnamed country, was taken from his cell, interrogated, tortured, and beaten nearly to a pulp. The one comfort in his life was a blanket. As he staggered back to his cell, ready to collapse into that meager comfort, he saw to his dismay that someone was wrapped up in it–an informer, he supposed. He fell on the filthy floor, crying out, “I can’t take any more! whereupon a voice came from the blanket: “Ivan, what do you mean, you can’t take any more?” Thinking the man was trying to get information to be used against him, Ivan didn’t explain. He merely repeated what he had said.
“Ivan,” came the voice, “Have you forgotten that Jesus is with you?”
Then the figure in the blanket was gone. Ivan, unable to walk a minute before, now leaped to his feet and danced round the cell praising the Lord. In the morning the guard who had starved and beaten him asked who had given him food. No one, said Ivan.
“But why do you look so different?”
“Because my Lord was with me last night.”
“Oh, is that so? And where is your Lord now?”
Ivan opened his shirt, pointed to his heart–“Here.”
“OK. I’m going to shoot you and your Lord right now,” said the guard, pointing a pistol at Ivan’s chest.
“Shoot me if you wish. I’ll go to be with my Lord.”
The guard returned his pistol to its holster, shaking his head in bewilderment.
Later Ivan learned that his wife and children had been praying for him on that same night as they read Isaiah 51:14: “The cowering prisoners will soon be set free; they will not die in their dungeon, nor will they lack bread” (NIV).
Ivan was released shortly thereafter and continued faithfully to preach the gospel until he died in his eighties.
Content from All That Was Ever Ours, Keep a Quiet Heart and Love Has a Price Tag.