A while back a friend recommended Wool by Hugh Howey. She described it to me roughly as follows: a city-sized group of people live in a dystopian underground silo because outside is dangerous. The rule is strict, and when somebody is convicted of a death-penalty offense, the sentence is to go outside and clean the sensors so those in the silo can continue to monitor what's going on out there. (The environment is toxic, which is why this is a death sentence.)
But wait, I said -- if somebody is being sent to die, what on earth is his motivation to help the people who did that to him on his way out? Why in the world would people actually clean?
My friend said that answering that would be a spoiler, but the "books" are not book-length and the first one is free (as a Kindle book). So onto the Kindle it went.
During our trip to Europe I was facing a smaller chunk of time on a plane -- not enough to start a novel, but about right for this. It's a nominal 56 pages -- longer short story or short novella or what, I'm not sure.
The first story stands alone; in fact, from what I've read, the author didn't intend to write any more than that. Midway through I thought I knew where it was going, and the author managed to surprise me later. Yes, we get an answer to my challenge to the premise.
Since then I've read the rest of the five-book series. (There's also a prequel series that I haven't read.) The books increase in length as they go, with the fifth a nominal 264 pages -- so still shorter fiction as modern trends go. The first one is free, the next couple are 99 cents, then $1.99, then $2.99.
Each of the first three books focuses on a different main character; the last two books have multiple foci. As the series progresses we learn more about the real power structures in the silo and how things came to be this way. The series ends in a satisfying place but there is room for more stories to be told.
The first book stands alone. The second can, but ends a little tantalizingly so I wanted to immediately read the next one. The third through fifth are more joined at the hip; I don't think it would be very satisfying to read 1-4 but not 5.
I recommend the series. I especially recommend investing an hour and a half (maybe less for you; I'm a slower reader) in the first book.