: The team discovers an employee at the smelter has been stealing and reselling confiscated firearms.

: Danny’s mother, Clara Williams (guest star Melanie Griffith), arrives on Oahu with a "bombshell". After decades of marriage, she announces she is divorcing Danny’s father because she is tired of waiting for her turn at a life of her own now that he has finally retired.

: One of these illegal guns was sold to a prominent defense attorney, Gerard Burns . Burns confesses to killing Ingram after discovering the agent was having an affair with his wife.

While the team handles the murder, two main characters face their own revelations:

: In a final, chilling twist, Burns reveals he also murdered his wife to grant her "dying wish" to spend eternity with her lover—burying her body behind the wall right next to Ingram. Personal "Buried Secrets"

: A persistent journalist, Shawn Hutten, corners Grover about an incident from his past in Chicago. Grover eventually confesses to McGarrett about a tragic hostage situation where he failed to prevent a father from killing himself and his infant son—the trauma that truly drove him to move to Hawaii.

: Dr. Max Bergman determines Ingram died from a gunshot wound. The bullet matches a weapon that was supposed to have been destroyed in a police smelter.

In the Hawaii Five-0 episode "" (Buried Secrets), the Five-0 task force unravels a literal and metaphorical web of hidden pasts when a routine home renovation turns into a grisly discovery. The Crime: Secrets in the Drywall