It began with the discovery of a giant coffin while excavating a burial chamber near Egypt's famous Step Pyramid. But further digging opened an underground labyrinth, a mega-tomb filled with over 100 coffins filling every inch of space. Burying all these people must have required a massive operation...so who was behind it? Filmed with unprecedented access, we join archeologists as they make each ground-breaking find and follow them on their mission to solve a 2,500-year-old mystery that could change what we know about Egyptian history.