Jamie Dornan is the actor who played the serial killer Paul Spector in the crime drama series The Fall. Normal people usually don't know what goes on in a psychopath's head so the actor decided to do a little experiment and he actually followed around a woman on the London underground.

He described what it was like, "I really kept my distance … she got off a few stops earlier than I was planning so I said right, I have to commit to this. I followed her around a couple of street corners and then was like: what are you doing? It felt kind of exciting, in a really sort of dirty way. I'm sort of not proud of myself. But I do honestly think I learned something from it."