Chin is questioned about his father's murder and how his relationship with Malia and her family could have adversely affected the investigation.

While a Navy Seal is on a secret mission, his young daughter is kidnapped; Danny must find $18.5 million in order to save his brother.

With the help of an ex-HPD officer-turned private detective, Five-0 tries to solve the homicide of a woman who was working for a hula dancing company that is actually a front for an escort service.

Five-0 investigates when a bomb squad is attacked and the culprit threatens to detonate additional hidden explosive devices unless arsonist Jason Sinclair is released from prison. Also, after Adam returns from the hospital, Kono realizes that they are being watched, and McGarrett prepares to take his relationship with Catharine to the next level.

While McGarrett and Danny attend a couples retreat in Maui to work on their partnership issues, Kamekona’s dangerous past comes back to haunt him.

Five-0 must work with rogue MI-6 agent Harry Langford to find a terrorist planning to cause nuclear reactors across Europe to meltdown. Also, McGarrett and Danny ask retired FBI profiler Alicia Brown to help them find their serial killer vigilante.