H.R.F. Keating: Inspector Ghote Goes by Train (UK 1976)
From the Publisher:
The assignment was routine: to bring a notorious confidence man, arrested in Calcutta, back to Bombay for trial. But Inspector Ghote devised a plan to make it almost a holiday - to relax on the Calcutta Mail as it surged across the breadth of the Indian subcontinent. But Ghote's fellow passengers soon prove anything but restful...
H.R.F. Keating: Inspector Ghote Goes by Train. Penguin, ISBN: 0140039724 (April, 1976), 218 p., £1.99 (?).