Last year, Ariana Franklin won the prestigious Ellis Peters Award for her first novel to feature Adelia Aguilar - a prototype pathologist from the 12th century, who is also a woman at a time when women might be witches but were not supposed to be doctors.

Now Adelia is back in The Death Maze (Bantam, £12.99) which, if anything, is a richer, more exciting book than her debut.

Set in the winter of 1172, Adelia is sent to investigate the death of King Henry II's mistress in a snowbound castle protected by a seemingly impenetrable maze, where she and her travelling companions are greeted by another murder victim, a mad housekeeper, treacherous bishops and, most frightening of all, the king's wife, Eleanor of Aquitaine.

The detail of medieval English life and politics are superbly described, as is the landscape, and Adelia's journey from the Cambridge Fens to Oxfordshire is brilliantly done. It is totally fitting that Ariana Franklin holds the premier award from historical crime writing, named in honour of the creator of Brother Cadfael, for surely Adelia Aguilar is Cadfael's logical successor.

Inspector Ghote of the (as it was then) Bombay CID, was created by author H R F Keating in 1964 and featured in two dozen novels over the years. After retiring the character some time ago, Keating now revives him in Inspector Ghote's First Case (Allison and Busby, £19.99), for which we should all be grateful.

Set in India in the early 1960s, when memories of the British Raj were very fresh, the young, newly promoted Inspector Ghote is persuaded to make discreet enquiries about the apparent suicide of a British "memsahib" who has stayed on in India after independence.

Although Ghote appears out of his depth (he always does), his dogged but very gentle investigative technique soon uncovers scandal and murder, though his quest for justice is not made any easier by having to contend with the demands of his heavily pregnant wife.

Inspector Ghote's great strength as a detective, and as a character, is that he is always under-estimated by his opponents. Such an overtly un-heroic character would not be convincing were it not for Keating's skill as a writer, portraying him with a graceful lightness of touch and great affection.

Italian settings are increasingly popular in crime fiction and serial killers have, worryingly, never gone out of fashion. Michael Morley combines the two elements in Spider (Penguin, £6.99) and even though Thomas Harris has covered some of the same territory, this is a gruesome, fast-moving thriller which belts along at a breakneck pace.

The author, as a day job, is a television producer famous for the documentary Murder In Mind about British serial killer Dennis Nilsen. The novel comes with a non-fiction afterword describing Michael Morley's encounter with Nilsen, which is more chilling than his fictional tale. Even more chilling is the observation that Nilsen, convicted of six murders (and suspected of several more), is eligible for parole later this year.

Whoever said truth was stranger than fiction was dead right.

Nowadays the idea of trains running to time is so far-fetched that a large suspension of disbelief is called for, along with a healthy scepticism about anyone who takes an unnatural interest in steam engines and train spotting. So I was surprised to discover how much I enjoyed Andrew Martin's Death on a Branch Line (Faber, £10.99), the latest in the 'Jim Stringer, Steam Detective' mysteries.

Set in the sweltering summer of 1911, with strikes, suffragettes and the threat of German imperial expansion all rocking the boat of Edwardian values, our splendidly bluff, Yorkshire railway detective's latest case starts with the arrival of a condemned man at York station, in a brief stop-over before an appointment with the hangman in Durham Gaol.

On the flimsiest of excuses, Jim Stringer sets off into the north Yorkshire countryside to foil a miscarriage of justice and he has just one week-end in which to do it. If truth be known, it is probably a diversion of his part, to get out of taking his strong-willed, would-be liberated wife Lydia on a week-end break to Scarborough and the delights of the Yorkshire Riviera. Needless to say, Lydia is not very pleased about this.

There's more than enough here to satisfy the steam train buff and the historical mystery fan, as the period detail is cleverly and lovingly done, though perhaps Stringer could do with being a little more socially ambitious given that he is so good at his job. But then, he's probably the biggest train-spotter there is and 'steam detective' seems to be the job he was born to do.

Mike Ripley is the author of the 'Angel' series and writes a regular column for the Birmingham Post.