In the Kewalo Basin of Oahu, a honeymooning couple was on a fishing charter with their guide when a large fiery metal object fell from the sky, followed by a large shooting ship. The three were shot dead.
After the opening sequence, McGarrett awoke with a start from a nightmare about his old Navy buddy, Freddie Hart., who died saving McGarrett’s life. He called Lou, who came over to talk.
As the pair sat in McGarrett’s backyard, facing the ocean, McGarrett told Grover he returned to Oahu to avenge his father’s murder. He also returned to recover from the loss of Hart. He jumped at the Governor’s Five-0 task force offer.
Meanwhile, Danny’s mother informed her son that she was going on a ride along with Grover. Danny was not happy.
The team met at the docks when the Coast Guard brought in the fishing vessel containing the three bodies. It had a gaping hole in its side, and Chin told McGarrett there were reports of a fiery object falling from the sky. McGarrett noted the appearance of carbon graphite. Chin said the three had been shot with 762 slugs, the kind from M-43’s. McGarrett surmised those weapons being used by the Chinese and Russian military. McGarrett ordered a GPS location of the Coast Guard’s finding of the boat and a 100-mile radial search of the area.
McGarrett then got a call from Jerry, who had heard about the boat and informed McGarrrett that he was dealing with the Black Unicorn, a Chinese spy satellite containing Chinese military secrets.
McGarrett took Jerry with him to Naval Intelligence but got the runaround. Kono called McGarrett as they were leaving and told him she was able to get something from the newlyweds’ cell, which had been located on the boat. McGarrett and Jerry did not know they were being watched by a Chinese woman, who was also at the scene when the team initially saw the boat.
Photos from the phone revealed a shooter with salvage equipment and diving gear.
Meanwhile, Jerry was in his basement when he heard sounds like someone walking. Then, he heard a gun click. Someone told him to turn around, and he turned to see the Chinese woman who had been watching him. She held a gun on him and asked about the satellite information. At first, he denied knowing anything, until she shot one of his monitors. Then, he went to get the information, pulled out a stun gun, and shot her to the floor with it. He then called McGarrett.
When McGarrett got to the basement, the woman was tied to a chair. McGarrett told her who he was, figuring she already knew, and held the photo from the couple’s phone in front of her, telling her he wanted her to tell him who the man in the picture was. She said his name was Quan Yung and her name was Zi Chen. She was with MSS, the Chinese CIA. She had been sent to stop Quan and to retrieve the satellite, which contained key military positions at sea. Quan was planning to sell the secrets to the enemy. It would make the US vulnerable to an attack. She suggested the two team up to look for Quan.
She already had traced him to an address she had not checked out.
McGarrett agreed to take her to the address but when they arrived, he tied her hands to the steering wheel of the Camaro while he and Danny went inside. They found three bodies in the house, a hard drive, and enough C4 to make a bomb. Zi joined McGarrett and Danny in the house. The three bodies were those of her team. After finding the C4, McGarrett slowly stepped around the bodies and found a bomb under one of the victims.
After the bomb squad came and disarmed the bomb, McGarrett got a call from Catherine. Intel had come back on Zi. She was Quan’s fiancé. Zi told McGarrett that Quan had tried to talk her into his plan and that when he disappeared, she knew what he had done. She said she was not a traitor to her country, but MSS held her responsible. She wanted to use a computer in order to try and triangulate a location on a buyer and/or broker for the secrets.
Eventually, a broker for Russia was located. McGarrett and Danny again took Zi along, but McGarrett again tied her hands to the steering wheel. When she heard shots fired, Zi kicked out the driver window and used a piece of glass to untie her hands. She saw Quan leaving the scene and gave chase. McGarrett exited the building in time to see both of them running down the street.
When Zi caught up to Quan, they ended up shooting each other. She managed to retrieve the hard drive from Quan’s pocket as McGarrett approached.
In the hospital, McGarrett told Zi the DOD had spoken to the Chinese Ambassador and arranged for her and her team to be returned home. He told her information on the hard drive had been destroyed and they were unable to retrieve anything from it. She should take it back home. He said it should prove to her that her mission was a success. She told McGarrett he had gained her respect.
McGarrett then secretly met a DOD official, giving him the flash drive containing the intel removed from the hard drive, which had subsequently been erased. The official congratulated McGarrett on a “job well done,” to which McGarrett countered, “Make it count.”
McGarrett returned home to find Jerry in his yard, with his suitcase. He told McGarrett he could not return home because of the presence of the Chinese spy and the safety issue it opened. McGarrett tried to reassure him, but to no avail. Jerry said he was moving in with McGarrett until things settled down. After a brief pause, McGarrett simply said, “ok” and told Jerry there had to be some ground rules laid down at the start.