Transcript for Following Wounded American Veterans on 'Sacred Journeys'
holiday season, we have a story about a fascinating trend in faith. Average Americans leaving their lives behind to go on a pilgrimage, from walking in the footsteps of Jesus in the holy land to, as you're about to see, searching for miraculous healing. This has never been captured on video until now. Glad you made it. So am I. Reporter: Every spring, wounded warriors travel to a remote city in France called Lourdes, where, in 1858, a peasant girl claimed to have seen the virgin Mary. And where the waters are now believed to have holy, healing power. I was hit by a suicide bomber. 52 people died that day. Watched my squad members die, so -- it's pretty traumatic. This trip helps me find solace. When I first got injured, when I was having nightmares, when I was having anger issues, I felt like I wasn't enough. Like I would have been better off dead. Reporter: These Americans are joining soldiers from around the world on an annual pilgrimage. Not all of them are believers. This is corporal Zachary herrick who had a grenade explode in his face in Afghanistan. I don't really believe. I believe there's a higher power, obviously. I believe that. But you know, I don't know what it is and, so, I just keep an open mind. Reporter: The best selling author and TV host Bruce Feiler accompanied the veterans. They have the best science. And they still are longing for something. Reporter: This story is part of an upcoming pbs series called "Sacred journeys" with Bruce Feiler, which follows Americans on six different pilgrimages. From Saudi Arabia to Japan to Africa. We pray, we dancing. Reporter: Even at a time when organized religion is under siege, pilgrimages are exploding in popularity. We live in a time where it's sort of a DIY time for faith. You have to make your own decisions and decide for yourself what you believe and what gives your life meaning, so, a pilgrimage, which at its core is a gesture of action, is a response to that. Reporter: So, what will happen in Lourdes? Where the catholic church even has a medical office on hand to document teaming. What we are looking for is to understand if a person was, indeed, really sick, if we have a true and real diagnosis for that disease. What was the prognosis of that disease? What was the treatment of that person receiving and was it lasting forever? Reporter: One by one, the wounded warriors, even corporal herric, enter these small grottos, where they are bathed in what is believed to be holy water. The shock of the water wasn't as bad as my emotions. That in itself was something to grasp. The following day, I felt a change within me. I wasn't having as much back pain. I wasn't having as much pain up my shoulder. For some reason, my face felt lighter. Reporter: Chris, who was blinded in Iraq, is on his third visit. After his first bath, he was disappointed not to be cured. But in the end, his wife says, he was healed in a different way. He wasn't cured visually, but he was cured in another way. Our family was very broken. After we came last year, he started stepping up to the plate and being the man that he was before he went to Iraq. Reporter: Ultimately, these soldiers know the point of a pilgrimage is not to look for a specific outcome, but instead to step into the unknown and perhaps to learn something profound about yourself. I love you guy, like, all of you have been beautiful and -- it's like watching you guys smile, like, that's -- An ancient urge now more popular than ever. And "Sacred journeys" premieres on pbs December 16th.
This transcript has been automatically generated and may not be 100% accurate.