The island of O’ahu goes on lockdown when Five-0 hunts a terrorist who starts using weaponized drones on civilians. Meanwhile, McGarrett and Danno must go for a mandated review with a psychologist, resulting in a session which looks a lot like couples therapy.

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.

It's Halloween and Five-0 must track down a serial killer who is copying murders depicted in a cult slasher film. Meanwhile, McGarrett must help Jerry after he is kidnapped by the counterfeiters he has been tracking.