Deranged

Yeongasi is a parasitic worm that can hijack the human brain. When the parasite matures inside a host, it triggers extreme hunger and thirst, driving victims to jump into water to release the worms. The parasites essentially manipulate the brain's signals to force hosts to seek water, where the worms can then emerge and spread to new victims.

Early scenes of victims found near rivers with no external injuries hint at the parasite's water-related life cycle.

ChoA Pharmaceuticals workers orchestrated the outbreak as a stock manipulation scheme. The original research team had discovered Yeongasi's brain-control protein while studying ways to treat diseases like Alzheimer's. When the company was sold, disaffected researchers reunited to unleash a mutant version of the parasite, artificially inflating demand for their treatment drug. They bought up stock before the outbreak and planned to profit by selling thousands of doses to governments at inflated prices.

The rush to hospitals and pharmacies for Windazole is shown as suspiciously coordinated early in the film.

Windazole was an anthelmintic drug developed by ChoA Pharmaceuticals that could supposedly cure Yeongasi infection. However, the company had deliberately created a shortage, only a limited supply existed because production equipment was mismanaged after the company was acquired. When patients took other anthelmintic drugs, they experienced extreme pain and often died, making Windazole seem like the only hope.

The government's demand for the drug's chemical composition hints that ChoA was withholding a cure they possessed.

Jae-hyuk realized that pharmaceutical companies could synthesize a drug using the same active ingredient as Windazole without needing the original formula. His scientific background in biochemistry allowed him to identify that an alternative compound with identical effects could be created. This breakthrough enabled other pharmaceutical companies to rapidly develop treatments, saving countless lives even without access to the limited Windazole supply.

His background as a former biochemistry professor is established early, giving him the expertise needed for this realization.

With the outbreak spiraling out of control and the conspiracy about to be exposed, the CEO proposed a government buyout worth 5 billion won to reveal Windazole's recipe. This was a desperate attempt to maintain control over the drug's formula while profiting from the crisis. Most officials refused the exorbitant price, but the Prime Minister was about to sign before the truth of the scam was fully exposed.

The CEO's refusal to disclose the formula during public hearings foreshadows his later desperation to control the outcome.

Other anthelmintic drugs caused agonizing deaths rather than cures because they killed the mature Yeongasi parasites inside patients, but the dying worms released toxins that proved fatal. Windazole worked differently, it apparently eliminated the parasites without triggering this lethal reaction, though the exact mechanism was never fully disclosed since the company kept the formula secret.

The first patient who claimed Windazole cured him sparks the national frenzy, but his survival remains mysterious.

When the brothers gained access to the storage facility where Windazole was kept, someone set the building on fire and sealed the door to trap them inside. They managed to escape the flames, but their informant, a former researcher who helped them, was murdered by the head of the original research team in disguise. The brothers survived through sheer determination and quick thinking despite being cornered.

The investigation has been building toward a confrontation at the storage facility throughout the second act.

The final scene reveals a body floating in New York Harbor, implying that Yeongasi has spread beyond Korea to the United States. This chilling image suggests the parasite is now a global threat and that the危机 is far from over. The brothers' hope for an overseas vacation is undercut by the realization that nowhere is safe from the parasite.

The family's discussion about vacationing overseas and whether foreign countries have the same drugstores plants the seeds for this ominous revelation.

Jae-pil investigated the deaths connected to ChoA Pharmaceuticals and discovered evidence linking company workers to the outbreak. He tracked down a former researcher who confessed that the original team had engineered Yeongasi to manipulate stock prices. This confession revealed the entire scheme: the researchers deliberately released the parasite to create demand for their treatment drug.

Jae-pil's guilt over losing his brother's savings in a bad investment drives his determination to investigate.

The murdered researcher who helped Jae-pil was revealed to be the head of the original Yeongasi research team and a close associate of the ChoA CEO. The CEO had worked with these researchers before the company was sold and was complicit in the stock manipulation scheme. When the conspiracy unraveled, the CEO tried to profit by offering the government a buyout, essentially monetizing the crisis he helped create.

The CEO's reluctance to disclose Windazole's formula during hearings hints at his deeper involvement.