The film depicts the titular fraternity's harsh initiation of new batch members as seen through the eyes of pre-med student Sid Lucero, played by Mark Gil in what is generally recognized as his breakout role.

Over the succeeding months, the fraternity masters submit the neophytes to a series of tests: Pacoy Ledesma (Ward Luarca) has sex with Jenny Estrada (Chanda Romero), a prostitute, which is recorded and shown to the group.

Sid's love interest, Mariel (Bing Pimentel), expresses concern for his safety, revealing that she lost her brother in a frat initiation rite two years before.

At the university's inter-fraternity talent show, Upakan, the AKO neophytes perform a drag rendition of songs from the musical Cabaret, with Sid dressed as Sally Bowles.

At that point, de Leon had directed three films, including his directorial debut Itim, and was also known for his cinematography work on Lino Brocka's Manila in the Claws of Light and Eddie Romero's Aguila.

After meeting Maceda, de Leon reached out to screenwriters Clodualdo del Mundo Jr. and Raquel Villavicencio, both of whom he had previously worked with on Kakabakaba Ka Ba?

[3] A casting call was announced for the film and by December 1980 there was a shortlist for all parts except for Sid Lucero, the narrator, as de Leon did not want the role to be played by a newcomer.

It was attended by those on the shortlist, as well as established actors such as Charo Santos and Jay Ilagan, both of whom had previously worked with de Leon on Kakabakaba Ka Ba?

[9] The song used during the graduation of the fraternity is the Latin hymn "Gaudeamus igitur," which de Leon first heard from the 1954 MGM musical film The Student Prince.

Although there was never a formal ban by the government on the productions of Evita, permission to produce the musical was orally denied or discouraged by members of the first family, namely Imelda and her daughter Imee.

[12] As such, de Leon was told by Maceda, who was a personal friend of Imelda, to choose between keeping the disco number or the Martial Law question asked during the electroshock scene.

The removal of the "Don't Cry For Me Argentina" number also prompted de Leon to cut out the story arc of Inventor's character, limiting her role to the opening scene.

[13] The film is generally viewed as an allegory of the martial law era of President Ferdinand Marcos, the microcosm of the fraternity mirroring the macrocosm of Philippine society at the time.

Batch '81 and Sister Stella L. reflected those times in exploring the creation of the fascist mindset, as exemplified by activist nuns and school fraternities.The anarchists tear apart a dummy in the course of their song.

Meanwhile, the SOS fraternity, dressed as Alex and his droogs from Stanley Kubrick's A Clockwork Orange, perform an original rock composition "Upakan '81" while attacking a life-sized dummy.

"[11] Among de Leon's early films, namely Kakabakaba Ka Ba?, Kisapmata, Batch '81, and Sister Stella L., which all delve into sociopolitical themes, only the electroshock scene can be seen as directly implicating the Marcos regime.

[11] The scene was based on the psychological Milgram experiment as de Leon wanted to demonstrate "that people will obey authority even if the consequences are serious as long as someone would take responsibility for their actions".

Beyond the overt reference during the rock number, Vera writes, "specific events are mirrored (a head dunked in a tank of filthy water; a man strapped to a chair; one film beginning with a gang rumble, the other ending with same), crucial themes echoed ("What's your decision?"

[28] De Leon prepared a speech, which was read by Tee Pao Chew of the Asian Film Archive, about martial law under President Marcos, as well as the contemporary political climate of the Philippines, saying:[18] That [it] still resonates in my country is concerning, although in some ways expected.

In this environment, extrajudicial killings continue unabated under the guise of a war against illegal drugs, the Constitution and rule of law are blatantly disregarded, political leaders and even Supreme Court justices are cowed into submission and a professional army of social media trolls viciously attacks online dissent.

History is being blatantly rewritten and the martyrdom of countless martial law victims is denigrated as stupidity and a dictator is given a hero's burial in the dead of the night.

We will not allow our country to be dragged back to those dark times—a situation best described by the blurb on the film's original poster: 'A secret world where freedom is obedience, and authority is violence.'

The playwright Luarca transported the story to a contemporary setting, including references to social media, allowing the play to serve as a commentary on the current state of the country.