I Think We're Alone Now trailer by Momentum Pictures

I linked to the teaser trailer before, thinking it might be a comedy, in the vein of The Last Man On Earth, but the full trailer is completely different.

After the human race is wiped out, he lives in his small, empty town, content in his solitude and the utopia he's methodically created for himself - until he is discovered by Grace (Elle Fanning), an interloper whose history and motives are obscure.