DI Alex Morrow and her team have been shadowing a woman suspected of being involved in a large drug-smuggling and money-laundering operation. Roxanna Fuentecilla recently moved from London to Glasgow in suspicious circumstances and Morrow's bosses want all the glory when she's finally arrested. But then Roxanna disappears. She's left her partner and her two children and something about the situation, and the children's evasive attitude, leads Morrow to question what's really going on.

In the nearby picturesque town of Helensburgh, Iain Fraser is struggling to live with his overwhelming guilt. Under orders from the infamous Mark Barratt he's just killed a woman and now he's left with blood on his hands. Meanwhile Miss Grierson, a former scout leader who left the sleepy seaside town decades ago, has returned. Allegedly she's here to sort out her recently deceased mother's estate, but Iain knows her mother died over two years ago and suspects she has an ulterior motive.