Not a typical series. The show is based on a sort of premise that crimes repeat themselves and for the first season it was tracking down a Jack the Ripper intent on replicating the original Ripper's crimes. And the following season follow suit to a degree but of course everything is updated and frequently contains a twist. The series relies on atmosphere and character relations, especially the growing respect between DI Chandler (Rupert Penry-Jones) and DS Ray Miles (Philip Davis). Chandler suffers from OCD and his fast track career is ended when he chooses to save his sergeant over capturing a criminal. Miles is a hard-nosed by the gut street smart cop. The two find themselves enmeshed in eerie crimes assisted by civilian researcher Edward Buchan (Steve Pemberton) who is a crime fan who surfers from guilt when his research can't save a victim. The shows get better from season to season and the third season two parter (episodes 3.5 and 3.6) will have you watching with the lights on. If you don't have patience for character development, I would suggest you just start with season two.
Review of Whitechapel
