Davis was born in Birmingham and after taking a degree in English literature at Oxford University, she became a civil servant. She left the civil service after 13 years, and when a romantic novel she had written was runner up for the 1985 Georgette Heyer Historical Novel Prize, she decided to become a writer, writing at first romantic serials for the UKwomen's magazineWoman's Realm. Her dedication of the book Rebels and Traitors reads: "For Richard / dearest and closest of friends / your favourite book / in memory", and the author's website relates: "I am still getting used to life without my dear Richard. For those of you who haven't seen this before, he died in October ". The author says in her publisher's newsletter: "The greatest recommendation I can give is that Richard, its first reader, thought it wonderful. He devoured chunks, demanding ‘Bring more story!’ even when he was in hospital. One of the last things I was ever able to tell him was that Rebels and Traitors was to be published by Random House, so I would be working with dear friends for his favourite book." Davis suffered from the eye condition keratoconus from childhood, and in adulthood had a corneal transplant, about which she has said: "A stranger's generosity freed me from years of pain and anxiety", and urges her readers to carry a donor card.
Writing
Davis's interest in history and archaeology led to her writing an historical novel about Vespasian and his lover Antonia Caenis, for which she could not find a publisher. She tried again, and her first novel featuring the Roman "detective", Marcus Didius Falco, The Silver Pigs, set in the same time period, was the start of her runaway success as a writer of historical whodunnits. A further 19 Falco novels have followed, as well as The Course of Honour, which was finally published in 1997. Rebels and Traitors, set in the period of the English Civil War, was published in September 2009, and in June 2010. Master and God, published in March 2012, is set in ancient Rome and concerning the emperor Domitian. In 2012, Davis and her publishers, Hodder & Stoughton in the UK and St. Martin's Press in the US, announced that she was writing a new series of books centred on Flavia Albia, Falco's British-born adopted daughter and "an established female investigator". The first title, The Ides of April was published on 11 April 2013 in the UK, and its sequel, Enemies at Home, was published in 2014, followed by annual additions, the latest as of 2019 being A Capitol Death. In an interview in 2019 Davis discusses her successful plan to write a novel set on each of the seven hills of Rome, starting with the Aventine Hill and culminating with the Capitoline Hill. Davis has won many literary awards, including in 2011 the Cartier Diamond Dagger of the Crime Writers' Association given to authors who have made an outstanding lifetime's contribution to the genre. She was honorary president of the Classical Association from 1997 to 1998.