The episode begins with Watson waking up with a start due to the loud noise of Holmes’ sound apps. Holmes thinks that this has been a slow week. Watson tells him that his father is in town for business and wants to have dinner. He points out to her that the man does everything electronically and he doesn’t want to meet his father. Just then Holmes hears a news of an unusual incident; a plane collision. They arrive at the scene. Gregson tells Holmes that this is a crash site and not a crime scene. Molinari tells Holmes that everything is under control. But Holmes walks around the scene. He infers that all the passengers were attorneys.
He notices a man whose leg has been amputated but he points out that there is no blood around the wounded area. There is also a blunt force trauma on his head. This proves that he was killed before the plane hit ground. The murder weapon was a very large wrench and the killer had to be in that very small plane carrying only three passengers. Watson thinks that Holmes is trying to keep himself busy in order to avoid dinner with his father. Holmes suggests that they should talk to the people who last saw the victims alive. Gregson talks to the owner of the plane company and he tells them that he and the Captain Joe Newel have been friends for the past twenty years. He also knew Walter Devlin as he flew with them often.
The other associates Hank Gerard and Ellie Wilson accompanied Devlin a couple of times. The man then says that Joe was ex-military and he didn’t have any temper. The owner then tells them about the security cameras that were put up in the parking areas. And he is confident that Joe has nothing to do with the attack on Gerard. Next, Bell tells Gregson and Holmes that the three attorneys were flying for a class action suit against a company, Carmanto Foods, that sold substitutes that caused cancer. The junior lawyer from Devlin’s firm said that there were a lot of arguments between the three lawyers about how to proceed. Gerard and Devlin had a lot of difference in opinion as Devlin wanted to settle and Gerard wanted to keep fighting. Gregson gets a message saying that they found the plane’s black box.
They hear the conversation that took place in the plane and Holmes says that they heard only Devlin’s and Ellie’s voices. He points out that Gerard did not say a word. He also points out that the pilot said that there were three people on the flight when it was supposed to be four. Holmes says that Gerard wasn’t on the plane. But Molinari reminds him that Gerard’s body was found in the wreckage. Holmes presents his theory that Gerard was killed elsewhere and his body was hid in the cargo. Devlin thought that Gerard missed his flight and he was yelling at the junior lawyer over the phone and then the chaos was about the plane crashing. Gerard’s phone is found but it is damaged. Holmes takes the phone and tries to retrieve a voice message.
He then concludes that Devlin and Ellie did not murder Gerard and Joe as a pilot would know not to dump extra weight in the cargo as it could lead to an accident like the one that they got into. So, the killer is still alive. Next, while discussing the case, Watson figures out that Holmes is scared of flying; and asks him how he traveled from London to New York. Bell arrives with the info that Charles Cooper, the owner of the plane company has managed to get the security footage. They see that Gerard was arguing with a man, no one recognizes. They ask if there are cams on the other end. Bart tells them that they were broken and not repaired. But Holmes takes a close look on the name on the mystery man’s sleeve and it reads: ARM TO.
Holmes fills in the remaining alphabets and it is CARMANTO. Holmes also sees an old pager on his waist. She then asks him to get ready for the dinner and Holmes says that his dad won’t show up. Watson then tells him that it is not a pager, it is an insulin pump. The mystery man is diabetic. Odd diabetic and working for a company that makes bad sugar! Holmes and Bell go to meet Ed Hairston. He says that he was giving Gerard information that would help him with the case; so he is a whistleblower. He says that Gerard was angry as Ed refused to testify and the argument was for the same. Holmes then leaves. He tells Bell that Ed is the weakest subject as he had Type II diabetes and this affected his grip. So he wouldn’t be able to use a heavy wrench. So, now they are left with the sand that they found on the seat of the plane. Watson meets Holmes father.
He then tells her about a nasty wound from his childhood. She wants to know more about Holmes and he asks her as to how is the sex between them. Watson at once realizes that he is not Holmes’ father and he says that he was asked to take the place. Holmes was right: “Dad never shows”. Holmes tells Molinari and Bell that the sand he found at the site was unusual and he takes them to the fuel tank of the wrecked plane. He pulls out some sand from the tank and he says that somebody put the commercial sand inside the fuel tank, causing the plane to crash. This means the plane was sabotaged. Maybe Gerard walked into the sabotage and he got killed. The sabotage was supposed to land the plane in the waters, thus wiping away the traces of sand.
But the body in the cargo made it cash prematurely. Watson is pissed and arrives home. Holmes tells her about the recent findings and also that he has narrowed down a suspect. But she doesn’t want to go with him. She is angry that Holmes hasn’t shared any of his personal life with her. Next, Holmes and Bell go to Bart’s house. Bart is a pilot with the plane company and this he hadn’t mentioned earlier. Holmes tells Bart that whenever he flew back from Miami, Florida, his plane would show an extra weight of 66 pounds equivalent to 30 kilos. Holmes deduces that he was smuggling cocaine. Bart tells him that he was fixing Cooper’s car that day and he was nowhere near the hangar. So didn’t do it. The next day, Cooper arrives at the station and tells him that Bart asked him to be his alibi and had confessed last night that he used to smuggle cocaine and that Joe threatened to expose him; and also killed Gerard as Gerard found him tampering with the plane.
The cops go to Bart’s house and they find that Bart has fled leaving the murder weapon behind. Holmes notices some marks made by brackish water. He also sees some oil cans on the shelves. He knows that Bart drove a Camry and the oil can on the shelves were for some high end vehicle. He opens all the cans and finds bundles of money in it. So, a guy decides to run and he leaves behind all of his hard earned money? The weapon and money were planted and now their doubts are on Cooper. Also, Holmes states that Bart is murdered and the body is hidden. Cooper denies the accusations and he doesn’t budge.
Watson is doubtful if Cooper did it but Holmes is very sure he did. Watson asks him about the scar on his wrist and he tells her that it was a childhood misadventure. She then leaves saying that she has an errand to run. Holmes always smelt glue on Cooper and now that smell has transferred to Bell. Bell is pouring water for Cooper and Holmes tells him to get a pitcher. Watson meets Allistair; the guy who posed as Sherlock’s father. She knows that Holmes hired him and Allistair tells her that they have known each other for a long time. He then states an incident where Holmes came home and he was very high and kept muttering a name over and over again. He tells Watson that name. Meanwhile, Holmes asks Cooper if he wants to urinate and he says a no.
He then tells him that last night when he struggled with Bart, Bart cut his side with a knife and that wound caused a lot of blood loss. That is why Cooper is drinking so much water and not urinating. He then says that he used the glue in his office to close wound as he did not want to get stitches and let that wound go on record. This is an old military trick. Cooper says that he cut his side with a sharp piece of metal in the hangar.
Holmes tells Cooper that they will find the body in either of the two brackish water bodies in New York as the wrench too was hidden in one of them. And then they will find Cooper’s blood on Bart’s body. Case closed. At home, Watson asks Holmes about “Irene”. The episode ends.