Troubled Blood

Troubled Blood won the Crime and Thriller Book of the Year award at the 2021 British Book Awards. It was also shortlisted for two Crime Writers' Association Daggers in 2021, the Gold Dagger and the Ian Fleming Steel Dagger, but was not named the Gold Dagger winner.

Troubled Blood is the longest Cormoran Strike novel at over 900 pages in the UK edition. The length reflects the scope of the cold case investigation — which requires reconstructing the world of 1970s London, tracing witnesses across decades, and building a picture of multiple overlapping crimes — combined with significant development of both Strike's and Robin's personal lives. Rowling has said the book's length was determined by the story rather than a target word count.

Significantly — whereas the earlier novels investigate recent crimes, Troubled Blood investigates a disappearance from 1974, requiring Strike and Robin to work almost entirely from archival evidence, elderly witnesses, and historical reconstruction. The novel alternates between the present-day investigation and reconstructed scenes from the past, functioning partly as historical fiction.

Troubled Blood advances their relationship significantly, ending in a way that changes the nature of their partnership. Readers who have followed the series will find this instalment the most direct address of the slow-burn tension between them.