The words on the cover under the title read: "Murder at the edge of the world" - and Mongolia is indeed a pretty remote spot for most of us. THE SHADOW WALKER opens in standard fashion, with the discovery of a dead body by a drunk staggering home after a long night, but the author quickly establishes his niche when the location is revealed as Ulan Bataar, the country's capital. The police cannot identify the corpse (the head and hands have been removed), then more bodies are found, all unidentifiable, with seemingly no connection between the victims. Could this be the work of Mongolia's first serial killer?

One person is following the crimes with interest - Nergui, ex-senior policeman, now promoted to the Ministry of Justice. Bored with the politics of his new desk job, he studies each crime-scene report, and is mostly pleased when his boss, the Minister himself, assigns him to solve the murders. Nergui's doubts concern working with his old police colleagues, most of whom are said to be unintelligent and involved in petty corruption to ease the burden of living in a relatively impoverished country, and who are jealous or suspicious of Nergui's success. Luckily, Inspector Doripalam is in charge of the police investigation and (like Nergui) neither stupid nor corrupt, so despite some tensions and rivalries, the two men collaborate. A rather touching friendship develops, mutual professional respect growing as the sense of rivalry recedes.

When an Englishman is killed in his hotel room in what could be a related murder, an experienced British detective, Inspector Drew McLeish, is sent from Manchester to "advise" the locals - though after an initial meeting with the British Ambassador, Drew is not sure whose interests he is there to protect. Most of the first part of the book is told through Drew's eyes, so we experience his impressions both of this fascinating yet hardly known country, and of Nergui and his investigation. I became absorbed in the characters and in finding out about traditional and post-Soviet Mongolia and its people. I particularly liked the surreal holiday camp in the Gobi desert, and the atmospheric description of life in various social strata of Ulan Bataar.

In the second half, the steam runs out slightly as all the avenues of investigation turn out to be dead ends. A few more characters are introduced to add momentum to the plot, but the main break in the case is a relatively coincidental one. Once Nergui and Doripalam begin to see the connections between the victims (which are not much of a surprise), everything falls together very quickly as a result of Doripalam spending a couple of hours on the Internet, which makes me wonder why he didn't do that at the outset. There are also some minor plot inconsistencies.

Regardless, the book shifts into thriller mode: a "race against time" as Nergui juggles the information he has managed to glean with the need to protect the innocent as well as to secure a positive outcome of the case. These aspects are slightly cliched but pacy enough, and there is a (somewhat predictable) plot twist at the end to sustain interest. The most successful parts of this book for me were the characters and interactions of Nergui, Doripalam and their colleagues. I'm curious to know more about them, as well as more about the challenges facing Mongolia as it transforms from a mainly nomadic culture into a modern, post-Soviet state, with its mineral riches and associated political intrigues.

The British characters - Drew, the Ambassador and his friends - seemed to fade out after their initial introduction, and I felt were stock types. The solution to the mystery is not particularly satisfying, but the book as a whole is a very good read because of the main characters and sense of atmosphere. It is an excellent foundation for what I hope will be future outings for Nergui.