Holmes and Watson must dig for clues as they investigate the murder of an archaeologist. Meanwhile, Sherlock falls out with Alfredo.
The team needs to unravel a conspiracy when the president of the United States becomes the latest POI; Finch considers drastic action to combat Samaritan.
After a shakeup at the GCPD, Detective James Gordon's moral compass wavers to the extent that he turns to the Penguin for help.
While Gordon investigates the inmate escape from Arkham Asylum, Theo Galavan plots his next move with his new criminal gang, the Maniax.
The team investigates the copycat murder of an unsolved case from 150 years ago that spawned a legendary ghost story. Gregorio is spooked when the case is connected to a recent seance and a local medium.