A case from 15 years ago forces Grover to take his family on the run when a dangerous mob boss tracks him down to seek revenge.

Five-0 must free McGarrett's mother, Doris, when Catherine informs them that she was captured and is about to be executed after attempting to free Wo Fat's imprisoned father. Also, Chin loses his appeal to have Sara's adoption delayed, and she must move to Mexico.

While Danny chaperones Grace’s winter formal, terrorists seize the venue and hold everyone hostage in order to kidnap a diplomat’s son

When working a murder case involving the illegal practice of shark finning, Five-0 uncovers the possibility that a former Nazi war criminal may be hiding out in an old leper colony in Hawaii.

McGarrett and Five-0 are captured and face certain death after tracking a dangerous nemesis to the Island of Lanai. Also, Grover takes his son to Chicago where he testifies against a dirty cop from his past.

When a man accused of killing his wife threatens to commit suicide, Grover reveals how he too was once on the brink of taking his own life.

Thanksgiving brings Grover’s parents and brother Percy Jr. to Oahu for a visit tainted by sibling rivalry, and Five-0 investigates a thief who is crushed to death by an empty safe.