"A drugs bust at 221-B Baker Street leads to a revelation regarding the victim's phone... but when Sherlock gets a call - and a ride - it's from the last person he suspected! With the serial killer revealed, Sherlock faces his most taxing criminal investigation yet. Can a man really talk his victims to death? Is Sherlock strong enough to prevail in the face of blind chance? There's only one way to find out! (W) Mark Gatiss, Steven Moffat (A) Jay (CA) Jake"