Kelly's debut,The Poison Tree, was a Richard & Judy Book Club pick, and was turned into a major TV drama.

[1] Her sixth novel, He Said/She Said, spent six weeks in the Sunday Times top 10 bestseller list,[1] and was also a Richard & Judy Book Club pick.

[2] In 2014, Kelly's novelisation of the Bafta-winning TV programme Broadchurch became an international bestseller.

[1] Her seventh novel, Stone Mothers, was later published under the title We Know You Know[3], and was selected as a Richard & Judy Book Club pick in 2020.

Her ninth novel, The Skeleton Key, was published in 2022 and it included references to a song that was created by Ben Walker, Kirsty Merryn and violinist Basia Bartz to accompany the book.