mm, mike mcgrath. >> reporter: how important was the communication?ation gave us the strength, the organization, the leadership, the inspiration, to continue to resist. >> reporter: when jeremiah denton was trotted out for a photo op, he told the world what really was going on, by blinking out the word torture in morse code. here's richard stratton. >> that was our fight in the prison camp. we didn't have airplanes. we didn't have guns. we were going to try to deny them the propaganda. >> reporter: there were attempts none succeeded. ed was beaten to death after he was caught. >> i heard him go out the ceiling. we said, well, the torture starts tomorrow. tey were right. they came in and tortured everybody in the camp. >> reporter: mike mcgrath was beaten within an inch of his life. >> that was a fan belt. they started beating us because they wanted to know who was involved in that escape. that was self-torture. i remember that. >> reporter: when ho chi minh died in 1969, the torture stopopped and thehe north s swi thee propaganda to make the hani hilt

. >> reporter: lieutenant commander mike mcgrath was a navy pilot when he was shot down over vietnam.e infamous hanoi hilton, enduring brutal interrogations. >> they tortured us. they broke every single one of us. >> i had a wife and three little girls back home. i certainly wanted to see them again. >> reporter: when navy pilot lieutenant jack inch was shot down, a captor amputate the his injured thumb with no anesthesia. >> no need for that. you have caused pain in our country. now it's time for you to suffer. >> the torture was just too painful, and so i gave in. and i felt very guilty about that. >> did you feel like you betrayed your country? >> i did. i did. >> reporter: devastated, lieutenant commander charlie plum eventually confessed to a higher ranking prisoner. the response? >> hell. everybody broke. there's not a man in this prison camp who was as strong as he wanted to be. >> reporter: they communicated at great risk through sign language and a complex morse code. >> that's us tapping in tap code through the walls. that was our line of resistance. >> that's what got us th