The Flying Doctors - Season 4 Episode 24 -

David, Kate and Paula go on a clinic run to where men are working in a mine. A man has cracked ribs, David advises him to stop working but he won't, the man also fights in a boxing match which he held at the bar. David finds out the man is taking drugs. David goes into the mine just as it is about to be blown up to rescue the man, they just get out in time.