Payback follows Lexie Noble as she becomes embroiled in a dangerous police operation to bring down a notorious crime lord. With an idyllic family lifestyle in the suburbs of Edinburgh, Lexie is unaware that her husband, Jared, has been laundering Cal Morris's illegal proceeds on a large scale. Jared's every move is being watched by financial investigators DC Jibran Khan and DCI Adam Guthrie, who are determined to use the Noble family to bring Cal Morris to justice.