Chin Ho has a hi-tech bomb strapped around his neck that will go off if he moves or if anyone tries to disarm it. Cut to: 48 hours earlier, the team is called to investigate the murder of an arms dealer, murdered two weeks ago, but who just washed ashore. Kono tracks down the body dump site which is a high-end condo/resort area and video surveillance footage of that location reveals that he'd had a meeting there with Victor Hesse-the man who killed McGarrett's father and whom McGarrett thought he'd killed. McGarrett and Danny go to Sang Min to get help tracking Hesse. Sang Min agrees but says his contact will only meet if he's present. At the meet, Sang Min manages to escape and following his trail leads Chin Ho to Hesse, who rigs him with the bomb. Once again Hesse has backed McGarrett in a corner. Hesse wants $10 million to deactivate the bomb and though McGarrett knows he can't trust Hesse, the $10 million gets him close. Since the Governor won't give them the money, they devise a plan to steal it from HPD evidence locker. Chin Ho's extensive knowledge of this locker makes us understand why HPD thought Chin Ho was dirty. McGarrett gets the money and meets with Hesse who then throws it into a fire. They struggle and Kono ultimately shoots Hesse, allowing McGarrett to deactivate the bomb. They save Chin Ho, and capture Hesse, but lost the money and the Governor is angry that they lost Sang Min. In prison, Hesse meets with Wo Fat, who wants to know what McGarrett knows about his father's last investigation.
Also, it's Christmas time in Hawaii and Danny is trying to set up the perfect Christmas for his daughter, Grace.