The formidable Det. Superintendent Elizabeth Bancroft is leading the charge against the violent Kamara gang. Meanwhile, DS Katherine Stevens is given a cold murder case. In 1990, Laura Fraser was stabbed 18 times in frenzied attack at home. As Elizabeth and Katherine's paths cross for the first time, Katherine finds that there's more to the Fraser case than it seems – and Elizabeth has some secrets in her past which may prove difficult to hide.