: Maura struggles with the fear that she may have inherited "criminal tendencies" or "the beast" from her father. Meanwhile, Jane tries to protect her friend as mob tensions rise.

: A young man named Colin Doyle is found murdered with an ice pick in his ear—a signature move associated with old-school Irish mob hits.

The Beast in Me Ending Explained: Is Nile Jarvis a Murderer?

: During the autopsy, Maura discovers that the victim is actually her biological brother . This reveals that her biological father is Paddy Doyle , one of Boston’s most notorious Irish mob enforcers.

: Aggie Wiggs (Danes), a grieving author who lost her son, becomes obsessed with her new neighbor, Nile Jarvis (Rhys), a real estate mogul suspected of murdering his first wife.

: The title reflects the inner darkness and "bloodlust" that Aggie discovers within herself while investigating Nile, eventually writing a book titled The Beast in Me about their mutual trauma and vengeance.

In this episode, detectives Jane Rizzoli and Maura Isles investigate the murder of an identity thief, leading to a major revelation about Maura’s biological heritage.

"The Beast in Me" is also the title of a starring Claire Danes and Matthew Rhys.