Undercover Marshall by British author Philip Harbottle (
ISFDB,
SFE) is his standalone western historical action novella, this one another extortionate water resource diversion dispute (3rd one we've gotten!

) where the titular law enforcement officer goes undercover as a brutish enforcer for the corrupt and murderous town authorities running the scheme, intending to gather the evidence to put them away under the law, if he can fool them for long enough…, free for a limited time courtesy of publisher Endeavour Press' Pioneering imprint.
This was originally published in 2002 by Robert Hale as part of their Black Horse Western line using the pseudonym Russell James, and is based on a short story by the late John Russell Fearn.
Currently free @
Amazon (available to Canadians & in the UK and pretty much everywhere else worldwide that Amazon sells, since this is being done via their KDP Select exclusive-or-else program)
Description
Sometimes the only way to catch a criminal is to be one…
The town of Dry Acres is under the oppression of a two-pronged, crooked alliance between jack-of-all-trades Mark Grayson and Sheriff Henry Binalt.
Having diverted the watercourse to his own ranch, Grayson has starved the local ranches – including the Dalman’s Roaring G spread – of water.
And Binalt’s high taxes to the homesteaders are starving the people off the land.
Fed up of all the corruption, the local newspaper editor, Gil Radford, tries to expose them both but ends up murdered before he can publish his expose.
Having witnessed his death, Radford’s niece, Ann Dalman, resolves to carry on the fight and calls in the help of his old friend, Blake Carson.
While Carson manages to flush out Grayson, Binalt is a harder nut to crack. All Carson can do is run for Mayor in the upcoming town election.
Determined to protect his secret interests and continue his illegal stint as Mayor, Binalt hires a notorious gunman to eliminate Carson – the outlaw Jeff Oakroyd.
But what Binalt doesn’t know is that “Jeff Oakroyd” is already dead at the hands of the law.
“Jeff Oakroyd” is in actual fact, Parry Kelby – a US Marshall from Caradoc City investigating the allegations and rumours swirlling about Binalt.
As far as Kelby is concerned, Binalt is guilty but he needs proof of his crimes.
However, Binalt is a slippery man and at any sign that a US Marshall is sniffing about, he’ll destroy anything that implicates him.
If Kelby plays this long undercover game right, he might just get all the evidence he needs and in the process, save Carson and the citizens of Dry Acre.
Can he fool Binalt long enough to bring him down for good?
Based on a short story by the classic Western writer John Russell Fearn, Undercover Marshall is a suspenceful, nail-biter of a novella – perfectly balancing out thrills with blood-pumping action.