The Magnus Archives: Jumpchain

From the introduction:

This world is not what it seems. Though this may seem much like the one you came from, monsters hide beneath the surface. They take many forms, from alley-dwelling mimics waiting to snatch away the anwary to walking, talking hives of parasites, danger can lie around every corner if you’re unwary. But monsters are far from the only thing out there. The Magnus Institute of London, England seeks to catalogue and research the occult in its many forms, and at the time of your entry into this world, the newly appointed Head Archivist, one Jonathan Sims, is about to discover more secrets than he bargained for.