In the episode, Joel (Pedro Pascal) and his partner Tess (Anna Torv) escort the young Ellie (Bella Ramsey) through a biological contamination area in Boston to reach the Massachusetts State House.

The episode introduced "clickers", mutated creatures who rely on sound to move, designed using prosthetics with the game's concept art as reference material.

The episode received several nominations at the 75th Primetime Creative Arts Emmy Awards, including Torv for Guest Actress in a Drama Series, and won Outstanding Prosthetic Makeup.

Ellie reveals the Fireflies have established a secret camp out west with doctors working on a vaccine to prevent infection, and her DNA may be key to ensuring success.

Joel demands they return to the quarantine zone but Tess, still skeptical of Ellie's immunity, convinces him to follow through with their arrangement as the Fireflies will still give them supplies.

As the group makes its way towards the Massachusetts State House, Tess discovers a pack of infected blocking their route, explaining to Ellie the fungi can sense uninfected humans across long distances and draw its hosts towards them.

He found the biggest difference was the inability to make changes after production; in game development, he is able to request changes to factors such as framing, lighting, clothing, environments and weather.

[5] Pedro Pascal (who portrays Joel) considered Druckmann the most open and excited of the show's directors, and Bella Ramsey (Ellie) found his feedback believable due to his proximity to the source material.

[10] Rotten Tomatoes listed the episode's title in December 2022 as "Cordyceps Ordo Seclorum";[11] Mazin clarified it was "an early idea" that was later replaced as "it doesn't really make much sense".

[12] An early version of the cold open featured an unseen individual hitting a door, later revealed to be Tess's infected son whom she locked in a basement as she was unable to kill him; it was cut before production as the writers felt it did not fit.

[13]: 3:18  Mazin ultimately set the cold open in Indonesia to disorient the audience, a technique he was inspired to use from Vince Gilligan's television work.

Mazin considered it illogical for soldiers to patrol so far away from the quarantine zone and felt replacing them with infected granted the opportunity to demonstrate the connectivity between the creatures.

The production crew converted a local business into a ruined salon and asked another if they would permit a stunt performer to fly through the front window.

[25] Paino designed the Indonesian lab with "big and sinister" air ducts; he kept the colors simple to maintain realism and avoid resembling science fiction.

The website's critical consensus said the episode features "a terrific turn by Anna Torv and monsters that fully deliver on their terrifying potential".

[38] Praise was directed at Pascal's performance for his restraint and Ramsey for their humor,[2][3] and Den of Geek's Boo commended all three cast members for acting "with intention", allowing viewers to witness their emotional foundations.

[41] Total Film's Bradley Russell felt she demonstrated Tess's emotional depth,[3] and Den of Geek's Bernard Boo found her performance sophisticated and heartbreaking.

[2] Conversely, Total Film's Russell considered it "a baffling choice and fundamentally silly",[3] and The Washington Post's Klimentov found it the worst sequence of the series to date.

[4][44] Several critics praised Druckmann's directing and Sereda's cinematography,[43][45] particularly during the museum action sequence;[39][46] Den of Geek's Boo called it "masterfully choreographed" and compared it to the video game,[39] and IGN's Cardy found it fit the inelegant aesthetic of the world.

[2] Total Film's Russell praised Druckmann's "keen eye for beauty in this shattered world", citing a shot of a frog on a piano as a standout.

[45] Reviewers lauded the production design;[6][42] IGN's Cardy considered it "one of the show's high points" with its visualization of nature reclaiming civilization.