A murder case hits close to home for Max when he is convinced that The Trashman, a serial killer with ties to his past, is on the loose. In order to convince Five-0 of his suspicions, Max reveals shocking information about his childhood.

A grisly murder leads Five-0 to discover a ritualistic killing on Halloween, and the evidence suggests that the murderer will soon strike again.

McGarrett and Grover must work together to protect national security after they are tasked by the Governor to serve a warrant to a young computer hacker.

While the team investigates a couple's murder in which their sons are the prime suspects, McGarrett is shocked when Aunt Deb returns to the island with her new fiancé.

McGarrett and Odell come under siege in Odell's barbershop when they try to protect a young man who is being hunted down by a gang. Also, Jerry is wrongfully accused of committing a series of home invasions.

When Five-0’s sketchy confidential informant is accused of murder, McGarrett asks his old friend Odell Martin to defend him.

While Five-0 investigates the theft of a high tech, indestructible suit built for the U.S. military, Jerry helps his sister try to save a captive elephant.

While McGarrett and Danno celebrate Valentine's Day with their girlfriends, the rest of Five-0 investigates the murder of a man taking a class on how to land women.

Five-0 helps PI Harry Brown work the case of a kidnapped wealthy woman whose husband may have something to hide. Also, Rachel tells Danny that she is getting a divorce from Stan.

Tani and Junior go undercover as prospective parents in order to infiltrate a private school where the headmaster was murdered. Also, Adam's life is on the line when he is held captive and forced to produce a hidden massive amount of money.

When the top salesperson for a beauty company/pyramid scheme is murdered, Five-0 sifts through a long list of possible suspects who would want her dead. Also, Adam befriends a homeless man estranged from his family.

Five-0 investigates the murder of a man whose body may hold the key to a 20-year-old case involving a kidnapped girl whose father never stopped looking for her.

On Valentine's Day, Tani and Noelani are held hostage during a convenience store robbery. Also, Five-0 investigates the hug of a Thai diplomat whose wife confesses to the crime, but Danny suspects she's covering for the real hugger.