Hooked is a new app trying to save fiction among the social media generation, one terrifying text message at a time.

"Our goal was engagement, getting teenagers and millennials spend time in a narrative and complete that story and not get distracted," said Hooked co-founder and CEO Prerna Gupta. "Horror was the first thing that clicked."

It's working. The app, which has been downloaded more than 20 million times according to the company, is quickly growing in popularity among Gen Z and millennials. Hooked went from about 200,000 downloads weekly at the beginning of the year to more than 1 million per week, according to mobile app analytics company SensorTower said. Overall, downloads have increased 8,992 percent year-over-year.

Most readers are between 18 and 24, with 69 percent under the age of 25. The average user, however, is 25, and more than half are female.

Hooked's premise is simple. Professional authors and users submit stories to the app with one caveat: It must be told as conversation between characters in text message form.

The majority of stories are about 1,000 words, or about a six-minute read. But as it grows, the app has commissioned more serialized stories told in chapter form. The majority of stories are user generated, but the most popular material is from commissioned work, Gupta explained.

Gupta co-founded Hooked with her husband Parag Chordia. The two met at Stanford 12 years ago, and had worked together on various app projects "at the intersection of entertainment and tech." Previously, they developed an app called AutoRap that was eventually acquired by music-making app Smule.

She eventually became Smule's chief product officer, but the couple decided to take time off to travel and pursue another passion project: co-writing a young adult sci-fi trilogy.

"Everyone said reading is dying," she explained. "We started to ask ourselves given our background as app developers is there something we can do to save fiction? How do we make fiction appealing to young people? Can we find a way instead of thinking of it as one book to think of it as a product? How do we make fiction as engaging as social media today?"

Eventually the book series turned into what is known today as Hooked. Gupta herself is a science fiction and fantasy fan, but they tried all genres on the app before finding horror was the one that attracted most readers.

"The more experimental forms of writing tend to start with things like horror," she explained. "Horror is a visceral and very universal genre. It appeals to our very basic responses."