Patricia Wentworth 
The Case is Closed [EPUB ebook] 

Hilary Carew sat in the wrong train and thought bitterly about Henry. It was Henry’s fault that she was in the wrong train—indisputably, incontrovertibly, and absolutely Henry’s fault, because if she hadn’t seen him stalking along the platform with that air, so peculiarly Henryish, of having bought it and being firmly determined to see that it behaved itself, she wouldn’t have lost her nerve and bolted into the nearest carriage. The nearest carriage happened to be a third-class compartment in the train on her right. It was now perfectly obvious that she ought to have got into the train on the other side. Instead of being in the local train for Winsley Grove stopping every five minutes and eventually arriving at 20 Myrtle Terrace in time to have tea and rock cakes with Aunt Emmeline, she was in a corridor train which was going faster every minute and didn’t seem to have any intention of stopping for hours.