A Torchwood mini-series called Children of the Earth.
It's basic premise was that an alien species learned that certain chemicals that children make act as a drug to their species, so they demand that humanity turn over 10% of it's child population or be annihilated. The governments capitulated and went along with them. To make it even worse, all the wheeling and dealing going on just really made me feel like they where dealing with the current US government, instead of the British one.
It really made me think about how the US Government would handle the situation. Now I'd like to say that our current government would not give in no matter what. But I can't say it without certainty. I feel pretty certain that our last Administration wouldn't have even considered the offer and would have fought no matter how hopeless the odds.
I find it sad that in today's world I can't really trust in my government to make the right choice, if a situation like that where to happen.