THR has the scoop and offers this in the way of a synopsis:

Plot details are being kept under wraps but the project is described by those in the know as a contained, gritty action thriller centering on an air marshall flying on a domestic flight.

Wadlow, who often does script work on his projects, is working with two unrepped writers to put the Non-Stop script together. Way to hang onto that indie cred, Wadlow.