Moriarty Makes His First Big Move Ahead of 'Watson's Season 1 Finale

Before his time at Scotland Yard with Sherlock Holmes, John Watson (Morris Chestnut) was also an Army medic, according to this week's episode of Watson. John and Mary (Rochelle Aytes) were enjoying another cozy evening coffee date when he was called back to the hospital by a former Army buddy of his, Dean Kett (Robert Bailey Jr.). Dean was experiencing prolonged delusions, which John believed were his fault because of what happened during their time in Afghanistan. 

John enlisted in the military to pay for his medical school education, but he never truly adopted the mindset of a soldier. He found a woman with a rare genetic condition in the Afghanistani village his unit, led by Dean, was staying near. John was performing an introductory exam on the woman when Dean told him they needed to leave the area immediately. However, John hesitated because he didn't want to let the woman go. That hesitation was enough time for a young boy to detonate a bomb built into his bicycle, killing two unit members and costing Dean his leg. 

In the present day, John was overwhelmed with guilt over what happened and was ready to do anything to figure out what was causing Dean's increased distress. As John focused on mending this critical relationship from his past, Moriarty (Randall Park) was finally making big moves. He may have successfully eliminated one of our fellows by the end of the episode, and John still doesn't know he has two traitors working directly under him.

Dean also held the belief that John was responsible for his injury and losing his leg when John refused his order to leave the village they were scouting because John had found a woman with an extremely rare genetic disorder. Dean refused to be seen by our detective doctor, so John put Sasha (Inga Schlingmann) on the case. She pretended to dislike John so that Dean would allow her to treat him, and John could monitor the situation from afar. 

The con was working until Dean slipped into another delusion and ripped out his IV wires. He threw Sasha into a medicine cabinet and took off. The team had to go into investigation mode to find him and bring him back to the hospital before the pain in his abdomen turned into something life-threatening. 

Sasha and Ingrid (Eve Harlow) went to Dean's house to investigate environmental factors that could have led to his worsening delusions. They found a stack of papers where Dean was tracking his workouts, kept in a secure lockbox. It turned out that Dean was working out to try to pass the ARMY fitness test and get himself re-enlisted. There wasn't time to confront that, though, before Mary received a call that Dean was on the helicopter deck of the hospital, waving at an incoming helicopter. John was able to talk him down back into his room, and the two shared a heart-to-heart before John explained that Dean's symptoms had worsened to a spreading paralysis. 

Dean had to be incubated, and John spent the night on the couch in his room, trying to think through solutions. The diagnosis occurred to him the next morning when he saw that Dean's urine bag was dark. The team had also stayed up all night and landed on the same conclusion. Dean had Porphyria, a condition where his white blood cells had no heme content, which caused them to malfunction. John put Dean on an IV to try to restore their normal function. 

The IV worked, and Dean was so grateful that he told John that he knew where his mysterious Afghanistan patient was living in the United States. John was able to reach out to his "genetic white whale" and continue the research he had dreamed of doing since first meeting her in Afghanistan. 

Professor Moriarty was up to his usual sneaky tricks, though his agent (Kacey Rohl) was still the one dispensing orders on his behalf. She paid another visit to Shinwell (Ritchie Coster) to express Moriarty's displeasure with the fake DNA samples he had sent the week before. It turned out that Shinwell had been doing some research of his own and threatened the agent by revealing he knew about her sick daughter. With leverage of his own, Shinwell hoped to get out from under Moriarty's thumb. 

However, they were interrupted by Adams (Peter Mark Kendall), who was staying late in the office. The agent pretended that she and Shinwell were hooking up in secret, which Adams seemed to buy, but we shouldn't underestimate the Croft twin just because he's not as overtly ambitious as his brother. Adams' interruption was enough to give the agent time to steal a soda can from his desk so she could run her own DNA sample without Shinwell noticing. 

The plot thickened when the agent also cornered Adams' girlfriend, Lauren (Amanda Crew), in a posh bathroom. She stole her lipstick and reported to Moriarty that she had "the DNA sample and the vector." The agent got a fright of her own when a different Morarity proxy approached her while she was visiting her sick daughter and returned the lipstick, warning the agent not to make any more mistakes. 

Lauren informed Adams during a pit stop at the office that her make-up bag had mysteriously returned. That was foreshadowing because she returned to the office later that night, and the audience watched her put on the controversial lipstick in the elevator on her way to see her boyfriend. Adams apologized for being so absentminded lately before the two shared a passionate kiss, and then the credits rolled. 

There's something definitely up with that lipstick, but is it going to kill Adams or just temporarily render him useless to John? The professor might have just taken our most emotionally well-adjusted team member off the board, and that is so not cool, dude. Randall Park better be back next week to explain himself, especially since the agent relieved Shinwell of his double agent duties while Adams was getting the kiss-of-probably-death. 

Part 1 of Watson Season 1's two-part finale premieres on Sunday, May 4, at 9 p.m. ET on CBS, with Part 2 following on Sunday, May 11, 2025. Episodes are available to stream the next day on Paramount+.