![Deep Swimming](https://image.tmdb.org/t/p/w500/fCifke6hZudMvV5nc4xJvW0dLnY.jpg)
The team looks into the death of a terrorist 30 years previously after his daughter receives an anonymous note claiming he was murdered - an investigation that takes them right back to the Greenham Common anti-nuclear protests.
Meanwhile, Sasha agrees to go for dinner with her ex-husband Ned, which he is hoping will lead to a reconciliation.