Call me old-fashioned, but ever since an early crush on Lord Peter Wimsey, I have rather expected my detectives to be in his mould. But for those of you less conventional, I offer you in passing three new crime novels featuring as their sleuths a eunuch, a nun and a sheep.

Yashim is a 19th century Turkish eunuch in Jason Goodwin's literary thriller 'The Janissary Tree' (Faber £12.99) who is called in to investigate the death of a girl in the Sultan's harem; Sister Pelagia is a geeky 19th century Russian nun who, through her remarkable observational powers is able to solve crimes, in 'Pelagia & The White Bulldog', the first of an amusingly offbeat trilogy by Boris Akunin (Weidenfeld & Nicolson £12.99); and Miss Maple (sic) is a surprisingly sharp-witted sheep who takes time off from grazing to solve the mystery of her murdered shepherd George in Leonie Swann's debut bestseller translated from German, 'Three Bags Full' (Doubleday £12.99).

Wimsey, meantime, has almost completely been replaced in my affections by the dashingly flawed D.C.I. Simon Serrailler of Susan Hill's powerful imagination. 'The Risk of Darkness' (Chatto & Windus £12.99) takes up where 'The Pure in Heart' left off when there were no leads as to the whereabouts of a kidnapped schoolboy. When another child abduction takes place in Yorkshire that could be linked to the one in Lafferton, Serrailler heads up there. What he finds is so unexpectedly evil that it puts one in mind of Conrad's 'heart of darkness', to which doubtless the title of the book alludes. Hill has a genius for tackling controversial issues head on whilst paying tribute to the quotidian detail of ordinary people's lives. This series has become indispensable for lovers of quality crime fiction.

Another kidnapping features in Mark Billingham's excellent new thriller 'Buried' (Time Warner £12.99), this time of a sixteen-year-old boy, the son of an ex-police officer. Bizarrely, there is no ransom demand and it falls to D.I. Tom Thorne to investigate anyone with a grudge against the boy's father. But the search throws up more questions than it answers and there are many heart-stopping twists along the way. This is the most cunning, multi-layered Thorne mystery yet which should confirm Billingham's reputation as one of the major players in the crime league.

Simon Kernick, who like Billingham is one of a talented crop of relatively new wave British crime writers, hits the spot with 'Relentless' (Bantam Press £10.00), his fifth novel set in contemporary London. His narrator, Tom Meron, an ordinary married father of two, receives a phone call from an old friend one Saturday afternoon. Nothing unusual about that, except that the friend is screaming in fear for his life and his last words, addressed to his killer, are the first two lines of Meron's address. This is one that gets you by the throat, shakes you all about, and won't let you go until you finish it about an hour later. Highly recommended to make a dull journey pass like greased lightening.

Carla McKay has been a fiction reviewer for over 15 years for the Daily Mail and has persuaded them to let her do a crime column of reviews of recent crime fiction once every two months or so.