Next Stop: Murder

I love a mystery in which the murderer is one of "us", and this one delivers, albeit in a meandering way. Although it'll keep you guessing until the end, some editing would have been beneficial. There is some pertinent backstory to Roz, a former detective heading on a trip to reconcile with her soon-to-deliver daughter. Wouldn't you know it . . . a huge storm, a murder (or murders?) and other catastrophes derail the trip. Stuck in a freezing train with no help in sight, what is a detective to do, but solve the murder herself?