The "Special Branch" is a unit originally created by London police in 1883 to fight against the members of the Irish Republican Brotherhood. It is generally responsible for collecting political information and to investigate any activity that may be a threat against the state (terrorism, extremist activity).
The story tells us Roger Seiter (writer) and his Belgian cartoonist Pierre-Yves Berhin aka Hamo, so is theoretically not of the "Special Branch" spring, even if the political dimension of the investigation is immediately evident, with the involvement of a very senior officer introduced in the ministries and the business world.
Otherwise, it contains all the atmosphere of nineteenth century London, cobblestones, carriages, costumes, everything is there. It must be said that the two authors are not at their first attempt, Roger Seiter with Fog and Hamo with Noirhomme. The design of Hamo's still a bit like Disney at first (especially one thinks Atlantis). Too bad so that the rendering of the decorations is not more searched.
Especially because the script is meanwhile well put together, in three volumes (The agony of Leviathan, Leviathan Run, Awakening Leviathan) and even if the end is guessed actually quite easily. The "special branch" uses highly innovative scientific techniques for its time (early stages of forensics with the autopsy and forensic science with the impression) that gives zest to the investigation.
The middle of the sea is also well restored, even if it is not as central prégnant and it can be with the series "Tramp", another police BD and navy.
Note that a new cycle is underway, with "London Red".