What's the song used in the new BBC drama trailer?

Can anyone identify the song? I've Googled the lyrics (the ones I can make out, anyway!) but no luck. It's a female singer and guitar, a bit Emeli Sande-ish, and the lyrics are something like "What's up with you lately, you ain't been like this before." Anyone able to place the song? It's rather nice and it's been playing in my head for days!