This Is How The Deadly Rain Wiped Out Everyone On The Rain

In The Rain, a Netflix original series out May 4, something is rotten in the state of Denmark. Only it's not queens conspiring to kill kings and marry their brothers, like in Hamlet — it's killer rain. The Rain, Netflix's first Danish show, is an addition to an already crowded genre: stoic teens weathering the apocalypse.

The trouble begins when dark gray storm clouds gather over a Danish city. These aren't friendly storm clouds dropping by to replenish crops; they're more like unsettling weather patterns Jake Gyllenhaal might battle in The Day After Tomorrow. But only Simone's (Alba August) family greets this progression with a sense of alarm. Simone's father (Lars Simonsen) drives furiously to stay ahead of the clouds and transports the family to a bunker. Their father, a member of the science organization Apollon, knows what Simone and her brother, Rasmus (Lucas Lynggaard Tønnesen), don't yet: The clouds are full of toxic rain. Here's what you need to know about how a raincloud became society's biggest threat.

Wrong. The raindrops carry a deadly human-manufactured toxin. The toxin's effects are swift and fatal. Immediately after coming in contact with the poison rain, a person begins to seize and convulse. In some cases, people vomit and foam at the mouth. It takes less than a minute for the person to die, but it is a very painful minute. One can easily imagine the devastating effects of a toxin that works this rapidly. In the initial downpour, the rain wiped out entire populations unable to find shelter.

The toxin — which has no official name – is transmitted by rainfall. Once in the water stream, it lingers and can continue to devastate the population. The toxin remains in all bodies of water, like lakes and ponds, rendering people susceptible to it even when it's not raining. Each downpour is another danger.

To make matters more complicated, a person can catch the toxin from other sick people. Since the toxin travels through water droplets, it can be transmitted through an infected person's breath. That means once someone is infected, not only is there no chance of survival — there's no chance to comfort your loved one in their final moments.

The stark and persistent danger of the rain is perhaps best communicated when, six years after the initial downpour, Rasmus steps into a puddle. Some members of the group want to shoot him immediately, before he starts manifesting any signs of illness and can infect the others. Others want him to check whether the water has seeped through to his skin — though that is a risk, should he be infected. Luckily for Rasmus and his traveling companions, the water didn't penetrate the boot. All is well.

Though we know how the disease of The Rain is passed on, the rules of surviving in this post-apocalyptic landscape aren't entirely clear. Where do survivors get their supply of clean drinking water? Can water be purified of the disease? Are all fruits and vegetables immediately toxic, since they were grown with toxic water?

And that's not even broaching the question of hygiene. How terrible do people smell after years of not getting wet? How does their hair stay so clean? How have Lea's (Jessica Dinnage) braces not decayed entirely by now?

Aside from food and water, a person needs regular access to shelter to survive this landscape — that's how Rasmus and Simone are able to last six years.

As to the toxin's scope, it seems that the rain has only impacted Denmark and parts of Scandinavia. Rasmus and Simone are currently in a quarantined area of Denmark; no one can get past the wall. The quarantine indicates that perhaps there are other uncontaminated regions trying to keep the rain out of the border.

For the most part, Simone & Co are too busy dealing with survival to wonder about existential quandaries like "Why is this all happening?" But that's the show's central mystery. Likely, the fatal rain has something to do with Rasmus and Simone's father's experimentations at Apollon. There, travelers encounter a suspicious proportion of former Apollon employees during their journey, leading us to believe Apollon warned their employees in advance. Rasmus and Simone spend the series orbiting the truth about their own family's involvement with the apocalypse.

Waterborne diseases, like typhoid fever and cholera, are extremely dangerous — but they're not transmitted by rain drops. That said, heavy rains and flood cause these diseases to spread more rapidly. The toxin in The Rain bears a slight resemblance to Legionnaire's Disease. People are infected with Legionnaire's Disease after inhaling water droplets that contain legionella bacteria. The disease manifests with pneumonia-like symptoms, however — not with convulsing and immediate death. So the disease in The Rain appears to be a fictional, worst-nightmare scenario.

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