The discovery of the Titanic in 1985 solved one of the great mysteries of the 20th century. But now, 100 years after the ship tragically sank on her maiden voyage, the shipwreck is at risk. Will the Titanic be lost again? National Geographic Explorer - in - Residence, Dr. Robert Ballard led the expedition that found the ship - now he takes a personal journey to save his greatest discovery. He re-traces the path of the Titanic from Northern Ireland to New York City, meets the families of victims and survivors, and examines the most serious threats to the ship's future.