Railway to the Grave is the seventh in Edward Marston's Railway Detective series. It's on sale at Kindle US for $0.99, which is a bit unusual since books in this series, other than some of the earliest ones, don't tend to go on sale in the US very often, and are rather pricey when not on sale. (They do, OTOH, go on sale reasonably often in the UK.)
Railway is not on sale at Kobo US, but since it's a sale price off of a digital list price at Kindle, it's probably matchable at Kobo. YMMV - read the thread on Kobo price matching.
Kindle US:
https://www.amazon.com/dp/B006WB7GP8
Kobo US (for price check/match):
https://www.kobo.com/us/en/ebook/railway-to-the-grave-3