Odd things are afoot in the Cleaners, which, for a company that regularly mops up magical messes involving garbage gremlins and dust demons, is saying something. Ben's powers have inexplicably returned, stronger than ever, but he's now plagued with an unquenchable thirst-fortunately just for water, not blood. Dani is distracted from her friend's unusual predicament by her rigorous training under the tutelage of her sentient employee manual (which she's starting to suspect isn't standard company issue). Not only that, but the elemental spirits that fuel her powers have become a little too high maintenance, demanding free will and other nonsense. Then information surfaces that offers new clues to the incident that killed Ben's wife and left him temporarily insane and dying of a Corrupt disease. Ignoring concerns about the volatility of his restored abilities, Ben and his long-time colleague, Lucy, arrange a stealthy fact-finding mission into unexplored Sewer depths, determined to discover anything they can about his murky past. The instant they embark, however, Cleaners HQ comes under attack, leaving Ben and Lucy stranded in enemy territory. Defying direct orders from the Chairman, Dani mounts a rescue, conscripting four elderly window-washers who have unprecedented access to the mysterious glassways the company uses for magical transportation and surveillance. As the team races to recover their imperiled peers, their every step closer enacts a deadly toll. And despite Ben and Lucy confronting living pockets of gas and fecal fiends, the greatest danger may lie in the revelations they unearth in the bowels of the Sewers. That, or the general lack of water fountains.