The 3rd episode of the first season or first series of the BBC tv series Sherlock finally features the arch nemesis of the great detective – Moriarty. The episode starts of with Sherlock meeting a convicted murdered in a foreign prison. The man, an English citizen , reaches out to Holmes who is bored and correct the prisoner’s grammar and tells him that it is an open & shut case; the man is guilty and hence there is nothing for Holmes to prove. Back in England, Sherlock is bored as he has no case to solve. He amuses himself by shooting holes in their wall, causing Watson to go and spend the night at his girlfriend Sarah’s flat. However the next morning an explosion on Bake’s Street brings a concerned John running back, only to find an unaffected Sherlock sitting with his brother Mycroft. Mycroft wants Sherlock to investigate the murder of MI6 employee Andrew West. West was found dead on a railway line, and an important flash drive is missing. Sherlock refuses the case, saying he isn’t at his brother’s beck & call.

Then the duo are called to Scotland Yard where a phone with a pink case (from the woman in the first episode) has been delivered. A photo of their basement is sent to the phone, and they head to to it and find a pair of trainers left there. A woman wearing an explosive vest is forced to call Sherlock on the phone and made to read a message to the detective – if Sherlock does not solve the puzzle in 12 hours, the explosive vest she is wearing will be detonated. As Sherlock & John examine the trainers in the lab, Molly Hooper, the lab technician with feelings for Sherlock comes in and introduces her new boyfriend but to her dismay Sherlock deduces that the man is gay. Sherlock makes out that the shoes belong to a schoolboy Carl Powers who had drowned many years ago. An underaged Sherlock had tried to investigate the boy’s murder but was unable to convince the police to take his theories seriously. He solves it from clues left on the trainers: Carl Powers was poisoned via his eczema medication. The booby-trapped woman is freed. Then a second image is sent to them – a blood stained sports car. Another hostage calls & gives Sherlock 8 hours to solve the mystery. The card of a rental agency is in the glove box. The agency owner has a distinct suntan and was recently in Colombia, and the blood in the car had been previously frozen, so Sherlock concludes that the lost man, Ian Monkford, paid the agency owner to help him disappear. Once again, the hostage is freed.

All this has led Sherlock to deduce that he is battling Moriarty as named by the killer in the first episode. Next, Sherlock investigates the death of a reality decorative show, Connie Prince, from tetanus. Supposedly, she cut herself on a nail, but the wound was made after her death. A blind woman calls, giving Holmes 12 hours in which to solve the crime. Sherlock pins the crime on the housekeeper, who murdered Prince by increasing her botox injections. Although Sherlock solves the puzzle in time, the bomber triggers the explosives when the hostage starts describing her kidnapper’s voice. The next image sent is of the Thames river. Sherlock & John find the corpse of a security guard there. A pair of bruises on the body are trademarks of “the Golem”, an assassin. The guard had realised that a recently discovered painting by Vermeer was a fake. An astronomy professor had talked to the victim about the painting, and is also targeted by the Golem. While Sherlock and John fail to save her life, they find a clue to prove the painting is a fake, saving a fourth victim. The museum curator tells Sherlock that the person ultimately in charge was called Moriarty. During gaps in between, John has been trying to investigate the death of Andrew West on his own to appease Mycroft. John is puzzled to hear that little blood was found on the tracks and just as Sherlock had deduced from afar, agrees that West was killed elsewhere, then dumped on the roof of a train. They confront West’s prospective brother-in-law, who confesses that he stole the flash drive and accidentally killed West, who fell down the stairs in a tussle.

Sherlock waits for John to go out and then arranges to meet Moriarty. He is met instead by John, who appears to taunt him before revealing that he is another hostage, wearing an explosive vest and having his words dictated. Moriarty shows up and turns out to be Molly’s boyfriend Jim. John grabs him, but lets go when a sniper aims at Sherlock. Moriarty leaves momentarily but soon returns, having multiple snipers target both Sherlock and John. Sherlock aims his handgun at Moriarty, but then changes his aim to the explosive vest, which he had thrown across the pool deck. The episode (and the first series) ends on this cliffhanger.