Secrets of the Dead

After a whole day of climbing through the jungle in extreme heat, the team has covered less than five miles.

But they are just over 600 feet below the summit, within striking distance of the holiest site in the Khmer world of the past.

-Maybe we will understand more tomorrow about why the king needed to come here.

At first light, the team leaves camp.

The sacred summit looms high above.

-It's really beautiful, but... it's going to be really steep at the end.

The jungle is now so dense, the LIDAR map is needed to safely plot the rest of the route.

-We are just on the ridge here.

We are going this way, and depending where the track will go, uh, it may be interesting just to divert rapidly to see that stuff.

A shape on the screen has caught Christophe's eye.

-[Christophe] Wow!

-There is a depression here?

-[Christophe] This is... -Yes, and where you want to see?

The structure looks man-made.

-Yeah.

It doesn't... doesn't look like any natural thing we have seen before.

But the foliage is too dense to find anything at ground level.

-Yeah, sure, it's very difficult sometimes under such vegetation to make sense of these kind of features.

A detailed archaeological investigation is needed to find out more.

But the suggestion of human activity here means the team is on the right track.