Ex-addict, cutter, and bipolar. 3 words that describe 23 year old Sienna Brooks. So how in the hell did someone as screwed up as her become Liam Payne's best friend? Or Harry Styles's ex-girlfriend? Dealing with your past isn't easy. But when your past comes back to haunt you, what do you do? What can you do? And when you hear those sirens calling? Do you stop? Or run away? 'Siren' is simply the emotional journey between two people.