Once upon a time the Mary Celeste was just a ship like any other, ferrying goods to and fro across the oceans -- at least, that is, until December 1872, when the Canadian brigantine Dei Gratia found the Mary Celeste adrift and abandoned. The ship showed no signs of a struggle. The cargo was intact. The lifeboat was missing, but the occupants of the Mary Celeste were never seen again. Learn how this story became one of the most enduring (and misunderstood) mysteries in maritime history.