Scene in los angeles. reporter: tonight, the first look up close at the 25-foot hole where a boy plunged into a terrifying ordeal. 13-year-old jesse hernandez, out celebrating easter at a park with his family, when he wandered off with friends into a restricted area and onto a maintenance vent. in seconds, he was gone. nobody could find him, nobody could hear him, nobody could see him. reporter: the boy trapped in this dark four-foot wide pipe. new footage showing the current of raw sewage snaking under the city of los angeles. after that fall, hernandez somehow traveling more than half a mile down a slippery, toxic tunnel. above ground, a desperate race against time. we did not give up, but i ll be honest, we did not think we d find a viable patient. reporter: crews lowering special floating cameras into sewer hatches. then a clue. one of the cameras saw some handprints on the sewer, inside the sewer. reporter: inside the pipe? yeah. reporter: little jesse s family,