Slough House is a dumping ground for British intelligence agents who've screwed up a case in any number of ways - by leaving a secret file on a train or blowing a surveillance. River Cartwright, one such "slow horse," is bitter about his failure and about his tedious assignment transcribing cell phone conversations. <br><br>When a young man is abducted and his kidnappers threaten to broadcast his beheading live on the Internet, River sees an opportunity to redeem himself. <br><br>Is the victim who he first appears to be? And what's the kidnappers' connection with a disgraced journalist? As the clock ticks on the execution, River finds that everyone has his own agenda.