def download(self, sub_url):
        """download and unzip subtitle archive to a temp location"""
        response = requests.get(sub_url, headers=self.headers).text
        soup = BS(response, 'lxml')
        downlink = self.base_url+soup.select('.download a')[0]['href']
        data = requests.get(downlink, headers=self.headers)
        z = zipfile.ZipFile(cStringIO.StringIO(data.content))
        srt_files = [f.filename for f in z.filelist
                     if f.filename.rsplit('.')[-1].lower() in ['srt', 'ass']]
        z.extract(srt_files[0], '/tmp/')
        return srt_files[0]