The documentary treats two interwoven subjects : a naval disaster and the world-famous Romantic painting that was inspired by it.
The 1816 disaster involved is the stuff of nightmares : a crowd of people forced unto an unsafe raft that is too small to hold them all. Day after day ever more passengers died - through violence, hunger, despair - until only a fraction of them survived, after hair-raising ordeals. Here the documentary examines several aspects, such as the physical and psychological qualities needed for survival or the effects of generalized insanity infecting a whole group. Since the topics include subjects such as murder and cannibalism, it is pretty clear that this is a documentary meant for a fully adult audience.
Now the documentary goes that extra mile by building a life-size reconstruction of the raft, based on contemporary descriptions. (Me, I rather like documentaries that involve the planting of noble trees, as opposed to the cutting of noble trees, but still : 10 out of 10 for scientific thoroughness.) It turns out that the raft was indeed as gruesomely uncomfortable and unmanageable as described, to the point where it could have been used as a torture instrument.
The painting too is analyzed and described, from a variety of angles which include its artistic quality, its models, its source material, its ideological message and its political impact. As a visitor to the Louvre, I once had the privilege of watching and studying "Le radeau de la Méduse" for an hour straight - and let me tell you, no amount of advance familiarity through imitations and reproductions can prepare you for its actual impact...