Series
There are 5 books in the Lockwood & Co. series.
In a London plagued by deadly ghosts, three young psychic investigators take cases the adult agencies won't touch. Armed with salt, iron, and reckless courage, they face the screaming dead in a haunted house where something far worse than ghosts is waiting.
All 5 books total 2,213 pages.
The Books Oracle — track the series you are partway through, and see what to read next.