Watchdogs is the fourteenth episode of the third season of the television series Agents of S.H.I.E.L.D. and the fifty-eighth episode overall.
When a radical group called the Watchdogs emerges with plans to eliminate the Inhumans, Agent Mack and his brother become caught in the crossfire. Meanwhile, Simmons discovers a powerful chemical compound that could alter the future for Inhumans.
In Naperville, Illinois, Alphonso Mackenzie returns to his family's home, now owned by his brother Ruben, who was recently laid off his job, and bonds with him as he prepares steaks and they fix their motorcycles. The two have different reactions when they watch a television broadcast of the Watchdogs destroying an Advanced Threat Containment Unit facility with an implosion.
Since Alphonso is closest, Director Phil Coulson has him meet Leo Fitz and Daisy Johnson there to evaluate the crime scene before other federal agencies can. Ruben, who does not know that "Alfie" is a S.H.I.E.L.D. agent, disapproves, but cannot stop his older brother from doing his job, which he believes is an insurance claim adjuster. Fitz discovers that the implosion was caused by Nitramene, causing Coulson to realize that Felix Blake, whose whereabouts became unknown after he left the hospital, must be involved with the now proactive terrorist organization.
At the Playground, Lincoln Campbell has returned from his assessment and Coulson has received the results, but Coulson wants to test if Campbell should become a field agent, so he invites him to assist in finding Blake in one of his safe houses.
Jemma Simmons becomes more proficient in her use of firearms because she has grown tired of others saving her. Melinda May gives her techniques to improve her skills; then May confides in Simmons that she is seeking Lash, but has been unsuccessful. Simmons advises May on how to find her ex-husband. According to Simmons, Lash is a creature of instinct and May's work is more for a doctor to decipher than a spy. The scientist further explains that she and Fitz have been working on a preventive cure for Terrigenesis which might work on Garner; May does not want to hear that there is hope for the murderer of Inhumans.
After an argument with Johnson about the violation of civil liberties where Alphonso defends the Watchdogs, citing that S.H.I.E.L.D. should be above Gestapo tactics, he returns to Ruben to find him drunk and upset. Alphonso learns that Ruben relates to the terrorists and can quote their propaganda directly; he also learns that their family home is in default and Ruben is becoming desperate.
Johnson, with a disappointed Fitz, enacts her plan and threatens Dallas Wyatt, a Watchdog member who did nothing but write his feelings online, to gain information on where they meet. She calls Alphonso and tells him of her actions, but reminds him that stopping them will keep others from being killed. The three go to the farm and send in a D.W.A.R.F. which conveys the voice of Blake giving instructions to his men. Suddenly, Ruben arrives on his motorcycle and, accidentally, alerts the Watchdogs to their presence. During the short-lived battle, Fitz is hit by a Nitramene bomb which attaches to his neck. Johnson hits a terrorist with a vibrational wave; other Watchdogs see this, but think that Alphonso emitted it.
Meanwhile, in Atlanta, Georgia, Coulson and Campbell enter a safehouse to find Blake there. However, Coulson soon realizes that he is talking to a hologram when Blake continues to engage him in speeches and long conversation. Coulson tests Campbell by ordering him to kill Blake; Campbell follows orders by attempting and passes Coulson's test of loyalty to S.H.I.E.L.D., not just to his girlfriend.
Johnson and Fitz capture the Oscar and eventually learn how to neutralize the nitramene. Oscar also reveals that the Watchdogs want to kill an Inhuman so they sent a team to kill Alphonso because they thought he was one.
As the Mackenzie brothers argue about the different secrets they were hiding from one another, the Watchdogs lead an assault against them in their family home. Alphonso uses the fact that the Mackenzies have "home field advantage" and ultimately kill the invading terrorists.
Later, Johnson and Coulson learn that the Attack on the ATCU Headquarters was a cover-up to distract that HYDRA stole something from the location. The wheelchair-bound Blake delivers a warhead to Giyera who promises him that he will provide Blake with warriors and weapons enough to destroy the "freaks".