A group mentioned in various notes found in the possession of Dr. Muelhoffer, a psychologist, and practitioner of Rippertech who was resposible for the death of Lord Arthur Cotterill, apparently in collusion with, or under orders from Herr Oberst Von Steinhagen, the German Military Attache to the German Embassy in London.
While Dr. Muelhoffer was brought to a sticky end, and Herr Oberst Von Steinhagen killed himself, it would appear that "The Night Watch" are a larger organisation, with some considerable power if they have people in such high political office.
They report, according to Muelhoffer's notes, to someone called "The Master of Night" who is suspected to be in Transylvania.
Clancey Trombley of the British Intelligence Service also confirms that "The Night Watch" are a group that British Intelligence have encountered, at least on paper, more than once.
It would appear that The Night Watch are interested in acquiring blueprints for various weapons, as they have also targeted one Professor Challenger in order to gain access to his designs.
"Fisk" also appears to have some links with The Night Watch, but whether he is an actual member, or merely connected to them peripherally, remains to be seen.