A simple poem?
I expected Gunga Din to be a novel. Even when I read that it was a poem, I still expected a lengthy story told in rhyme. Instead, it's but a simple five paragraph poem about a soldier who realizes the error of his ways when the regimental bhistri dies pulling him to safety. The writers at RKO took a simple tale of sacrifice and turned it into an epic story involving the resurgence of a blood cult. That's incredible.
Seriously, if you haven't read it, go ahead and do so. It won't take five minutes.
http://famouspoetsandpoems.com/poets/rudyard_kipling/poems/14458
My hat is off to them for coming up with such a fine tale.