The short story Serial, by Blake Crouch & Jack Kilborn (J.A. Konrath), is free in the Barnes & Noble store. The format is most likely their own ereader format (although sometimes you do get an EPUB format), with DRM and not Kindle compatible.
Book Description
Remember the twin golden rules of hitchhiking? #1-Don't go hitchhiking, because the driver who picks you up could be certifiably crazy. #2-Don't pick up hitchhikers, because the traveler you pick up could be raving nutcase. So what if, on some dark, isolated road, Crazy #1 offered a ride to Nutcase #2...
This title was previously free in the Kindle store, but is no longer available there. Instead, the authors have released an updated and expanded version, Serial Uncut, which now is approximately 36,000 words in length and is sale-priced at $1.99 "for a limited time."
Book Description
Remember the twin golden rules of hitchhiking?
#1: Don’t go hitchhiking, because the driver who picks you up could be certifiably crazy.
#2: Don’t pick up hitchhikers, because the traveler you pick up could be certifiably crazy.
So what if, on some dark, isolated road, Crazy #1 offered a ride to Crazy #2?
When Blake Crouch (DESERT PLACES, ABANDON) and Jack Kilborn (AFRAID, CHERRY BOMB), face-off, the result is SERIAL, a terrifying tale of hitchhiking gone terribly wrong. Like a deeply twisted version of an “After School Special,” SERIAL is the single most persuasive public service announcement on the hazards of free car rides.
Beyond a thrilling piece of horrifying suspense, SERIAL is also a groundbreaking experiment in literary collaboration. Kilborn wrote the first part. Crouch wrote the second. And they wrote the third together over email in 100-word exchanges, not aware of each other’s opening section. All bets were off, and may the best psychopath win.