'Watson' Goes Dark in a Game-Changing Finale

John (Morris Chestnut) may have discovered that Moriarty (Randall Park) is still alive in part one of the Watson finale, but that didn't give him a lot of ideas about what to do with the supervillain in the concluding hour of Season 1. Before John could figure out what to do about his nemesis and his best friend's killer, he and the team had to figure out which Croft twin (Peter Mark Kendall) to save. That was no easy task, considering both twins were an integral part of the team, and there were emotional attachments on all sides. 

Ultimately, it came down to a coin toss, and Adam won. He was given a single dose of the anti-viral and brought out of his coma so the team could start working on backup ideas to save Stephens as well before the virus caused irreversible brain damage. The team needed to use everything at their disposal to come up with a solution, but that was made more complicated when Shinwell (Ritchie Coster) revealed Moriarty had also poisoned him, and Ingrid (Eve Harlow) was struggling with which side of the fence she wanted to be on. Was it worth trying to redeem herself after she destroyed the samples that could have saved both twins, or was it better to just make the jump and join Moriarty on his mission? The evil professor at least seemed to appreciate her talents. 

It would take every member of the team to pull of a medical miracle and finally give John the upper hand, but what he decided to do with it was pretty damn shocking. 

Shinwell returned to the Holmes Clinic with some leverage that John could use to find Moriarty's weakness. John knew that Moriarty must keep cures for the viruses he created just in case they ended up in the wrong hands or backfired on him. The team needed to get Moriarty's anti-viral for Stephens, but that would require understanding Moriarty's network and where he kept his materials. Shinwell provided that access by bringing The Rep (Kacey Rohl) and her sick daughter to John for treatment. 

John agreed to help The Rep's daughter, who had a brain tumor that couldn't be treated with chemotherapy until the small girl gained 15 additional pounds, in exchange for information about Moriarty's lab. There was some initial back and forth about whether The Rep should risk her life by betraying Moriarty when she had no guarantee that John would help her daughter once he had what he needed or if he even could. 

She was lucky that John Watson was a man of morals—at least in this regard—because he would not turn away a sick child. The Rep worked with Shinwell to figure out exactly where Moriarty's lab was and thus where the antiviral for Stephens was most likely held, while John and the team worked on what was keeping the little girl from gaining the weight she needed. 

The answer to the medical problem was a genetic mutation that prevented our patient from processing the protein formulas she was being given for nutrients. All the team had to do was switch the recipe for her protein shakes, and the weight started to be added on. 

Meanwhile, The Rep and Shinwell found the lab and were about to storm in to get the cure for Stephens when John suddenly called them off the case. He did it just in time because it appeared Moriarty had figured out they were there and sent security reinforcements to stop Shinwell from getting inside. Unfortunately for Moriarty, that was also part of John's master plan. 

Ingrid struggled with what she was ultimately going to do throughout the episode. She was racked with guilt about what she had done to the twins, and Moriarty offered her an escape by joining his team. She'd probably even get to keep working on finding a cure for her sister's paralysis, and she wouldn't have to look her team in the face every day. The deal was pretty tempting, but Ingrid ultimately decided not to take it. 

The audience didn't know that when she arranged to meet with Moriarty at the cable cars, and told him the team's plan to get into his lab and save Stephens. It really looked like Ingrid was selling everyone down the river, but it turned out that she had already confessed everything to John the night before. He took a page out of Moriarty's book, created his own virus specific to Moriarty's DNA, and had Ingrid spread it over the cable cars hours before her and Moriarty's meeting. 

Whatever John had concocted caused Moriarty to go blind within a few hours, bringing him stumbling into the Holmes Clinic, begging for help. John used Moriarty's weakened state to extort the cure from Stephens out of him in exchange for his own antidote. Moriarty gave the team the anti-viral they needed to save Stephens, but John didn't hold up his end of the bargain. 

John decided to withhold the cure from Moriarty, despite it directly violating the Hippocratic Oath. John argued that the oath made him swear to do no harm, but what did that mean when Moriarty was the harm? In John's mind, allowing Moriarty to die was doing the world a favor. That is definitely a take, and a bold swing for Watson to make their protagonist a murderer. He did it for the "greater good," but it would still be first-degree murder in a court of law, premeditation and all. John seemed to be okay with that, watching Moriarty die in his hospital bed. The last we saw was John closing Moriarty's eyes and exiting as Mary (Rochelle Aytes) into the room alone, raising some questions for Season 2. 

Did Watson just kill off the biggest antagonist in the Sherlock Holmes lore in Season 1? Was it to save them from paying Randall Park to appear in Season 2? Was it because the show finished filming months ago, before the Season 2 renewal, so they wanted to ensure fans had a satisfying ending to the Season 1 arc? Or is our supervillain dead? The questions for this dark swing create an interesting situation for the next season. Either John and his team move on to face other Sherlock and original foes, or Moriarty has found a way out of this tight situation. Perhaps, Mary was also secretly working for the professor all along, creating a fascinating dilemma for John in the second season. 

We'll have to wait and find out. Watson has been renewed for Season 2 and will return on CBS in the 2025-26 TV season. Season 1 is now available to stream on Paramount+.