Some years ago there was a documentary on this that was very well done.
As will this be: "So large do their exploits loom, that a television mini-series starring Edward Norton as Lewis and Brad Pitt as Clark is currently under production in the US."
A brief clip from the Ken Burns documentary “Lewis & Clark: The Journey of the Corps of Discovery” describing the death of Lewis.
http://www.youtube.com/watch?v=dAb-2BDGvAc