Mostly shot in Belgium, with only a few scenes shot in London and Paris.
Tchéky Karyo (who played Baptiste) went on to star in the spin-off series Baptiste, which aired from 2019 to 2021.
James Nesbitt and Ken Stott previously acted together in Peter Jackson's Hobbit trilogy: The Hobbit: An Unexpected Journey (2012),The Hobbit: The Desolation of Smaug (2013), and The Hobbit: The Battle of the Five Armies (2014).
The book being read by the 13-year-old boy in the first episode is "To kill a mockingbird" by Harper Lee.
James Nesbitt and Jason Flemyng have both portrayed Dr. Jekyll & Mr. Hyde in different adaptations, the TV-series Jekyll (2007) and the movie The League of Extraordinary Gentlemen (2003) respectively.