Founded in 2015 by former Penguin Random House global digital director Molly Barton and co-founder Julian Yap, Serial Box is just one more example in a never ending list of digital operators that are stealing readers from mainstream bookstores and online stores, creating the fallacy that people are reading less.

Serial Box is a clever play on words as the business model is teams of writers delivering weekly-serialised content on the TV model, which consumers (readers and listeners) can buy by the episode or as a full series.
From the Serial Box About page:

While technology has rapidly evolved, the way publishers and writers bring books to readers really hasn’t. Storytelling in TV has become more sophisticated and multilayered, podcasts have risen to mainstream media status—but ebooks are just books on digital devices, not easier, more fun, or more social than they were before.

Now Serial Box has picked up $4.5 million in funding and topped that with an announcement it had partnered with the king of serial content, Marvel Comics.
Starting with Thor this summer, reports the New York Times, Serial Box’s stable of 100 authors will produce serialised original content, serialized, for Thor, Black Widow, Jessica Jones and Black Panther.
Barton told the New York Times there are plans for television adaptations from some of the Serial Box original content, but gave no further details.