... we're leaving tonight when it gets dark..." this is all I remember from it.

I heard it 3 days ago, it is sung by a girl, and she sounds a bit like Ellie Goulding, it is - as far as I remember - similar to her song "Under the Sheets".. but probably it is someone else...

tried to google the lyrics, but didn't find anything. Any ideas? I would be so happy if you could help me greez from norway.