The episode begins with a warehouse on fire. The crew manages to get the raging fire under control. Finally, when the fire is out, they find a body and call for the arson unit. Just then they find a classified file next to the body and the Navy is called. Ziva and McGee arrive at the scene. The warehouse is owned by United Equinox electronics and they make modems to toasters. They also worked on top secret weapons. Just then Gibbs walks in and hands over the classified file to Tony and tells them that they are here for the file. They enter the warehouse. Just then Jason King from Baltimore PD arson unit recognizes Tony. He says that he was in homicide for two years before he made it to arson.
They two don’t seem too friendly. Duckie tells the team that the victim can be identified only through his dental records. Jason thinks that the fire was started somewhere near to the victim with a flare. Jason said that the arson used was really strong and that it nearly burnt everything. But then he points out to a drawer with busted lock and is empty. Mc Gee arrives and tells the team that the last person to enter the warehouse was Carter Plimpton; 40 minutes before the fire was reported. Gibbs declares this to be an NCIS case and tells King that he is with them now on. At the lab, Mc Gee finds out that Carter was an analyst at Equinox. Tony tells the team that he met Jason only once; twenty years ago and then Jason was nine. Just then Gibbs walks in and posts a photo of the Phantom 8 on the screen. That is the Navy’s Watcher group.
Gibbs points out that Carter was a part of the Phantom 8. At the lab, Jason and Duckie are examining the body. Gibbs walks in and Duckie finds the burns unusual; the victim’s skin was double burnt and that the victim was tortured before his death. After a point the killer stopped as he got what he wanted. Ziva and McGee go to the Equinox lab and meet Jack Murdock. He tells them that Carter was in product testing. He says that there is nothing in the warehouse which could be top secret information. Jack also says that he doesn’t know about the Watcher fleet. Next, Abby is watching Myth Busters, playing in the lab and Gibbs walks in. She tells him about thermite reaction which she found on the victim. It burns through metal but also had an added component to the slow burn. Next, Tony tries talking to Jason but he doesn’t want to talk. Tony figures out that he hasn’t forgiven him about his sister and Jason confirms that Tony is thinking right. McGee tells Gibbs that he hacked into the Navy Intelligence Database and found that the Watcher fleet was working on a project called Aquamarine.
There was a file at the warehouse with the same name. He doesn’t know much about the project but it was initiated four years ago, when Carter was in the Watcher group. Someone was looking for Navy secrets. They also found that Carter left navy to join Equinox for the Aquamarine project. They start looking for what the killer left behind. Jason tells them that not many arsonists use thermite. So it would be easy to narrow down their search. McGee gets a hit on Billy Wayne who has used thermite for committing crimes but is in prison. But they could get an idea talking to him. They call Billy in. Billy tells Gibbs and Ziva that one doesn’t need thermite to burn papers. They would have either done it for fun or send a message. Also the person who did this is practicing for a bigger event.
He tells them that he has a slow burn thermite recipe and that he had once mentioned it to Janice; she was writing a book. In the lab, Abby is showing Jason her termites test. Jason tells her that he got into arson because once when he was a kid, he was caught in a fire and they never caught the guy. McGee is trying to trace Janice. Just then he gets an alert about a suspicious blaze, just a mile away from the warehouse. The team reaches the scene. There are no injuries but some tarps on top of the cargo hold were burnt. The hold was empty and it showed signs of thermite. Next, Jason follows a trail of some smell. Tony follows him. Following the ship’s wiring, he reaches the fuse box room. When he opens the fuse box, it sparks and a fire quickly spreads through the wiring. Jason quickly moves Tony out of the way. He tells Tony that it was a trap and they almost got caught in it.
He tells Tony that now they are even. At the lab, Abby tells Gibbs that the source of the fire was not a bomb. Somebody had set a thermite charge in the insulation box, causing the insulation wires to carbonize. Whoever set the fire knew that the wiring was flawed. The wiring was made by Equinox. McGee and Gibbs go to Equinox to meet Jack. They show Jack the internal memos from Carter requesting an inquiry. Also Carter had requested a recall inquiry nine months ago. Jack tells them that this sort of a thing is extremely rare and that there weren’t enough proven cases of flash over to legally warrant an inquiry or recall. He once again tells them that he has never heard of the Watcher fleet. Next, Ziva and McGee show Tony a picture of him carrying a young Jason out of a fire.
Tony tells them that he was in Baltimore for the Final Four and that one night when he was taking his walk, he saw smoke and heard screaming from a townhouse. He went in. but he says that it was more complicated than that. In the flash back, Tony walks through the hallway following the cries for help. He finds Jason in a closet and gets him out. On their way out, they heard Jason’s four year old sister cry for help. But just then the ceiling collapsed. Jason had to make a choice. He left the building with Jason; leaving his sister behind. Just then Gibbs walks in for a report. They find out that Billy made a call from prison to Mary Gardocki aka Janice. Next, Gibbs interrogates Mary and learns that she is a sales representative for a chemical company and sells napalm. It is legal.
He shows her a picture of the Watcher fleet but she has heard of them; never seen them. Gibbs sees that she is wearing a scarf. He removes it and sees that she is burned. She tells him that she is developing a slow burning thermite with Billy and was in the burn center for the last three days. They confirm her alibi. Also according to Jack’s list, there is no report for faulty wiring. Abby asks Gibbs to come to the lab. Abby tells him that the secret ingredient is ammonium phosphate and is used in fire retardants. Now, this brand of retardant that the arsonist used is exclusive. They run a check for the buyer and get a hit. Jason recognizes him as the fire department site inspector on both the sites; Bruce Johnson. Gibbs is irritated that Jason didn’t realize that he was an impostor. They go to Bruce’s house. He wants a deal.
Bruce tells them that the guy who hired him wanted Carter’s information on bad wiring. He didn’t want to kill Carter, but Carter refused to give him any information. Gibbs asks him to turn off the car and the moment he does, the car explodes. Jason tries to rescue Bruce but Tony stops him. Ziva finds the missing file from Equinox in Bruce’s house. It has the list of every warship with faulty wiring. They did sell it to the Navy. They deduce that the current Watcher fleet is working with the Navy to fix the problem but only one third of the fleet has been retrofitted so far.
At the offices, they try calling everyone to notify them, but since this was a top secret project to protect the Navy, who would know. Jason and Tony clear the air between them. Gibbs wonders if the Watcher fleet microchips had the information on the faulty wiring. McGee says that it is possible but they are all accounted for. At the sea, on the USS Brewer, a sailor sees light from inside the machine room. He goes to check it and just then the door explodes. The episode ends.