Holloway and Blakemore investigate when Thea Ashwood, a 'Bolinger socialist' and environmental activist, vanishes mysteriously. Meanwhile, Sykes investigates when a triathlon swimmer disappears during a race.
Holloway and Blakemore investigate the disappearance of an environmental activist who they believe is responsible for an explosive protest that put one man in hospital. Sykes tries to determine what happened to a triathlon competitor who vanished during a race that was being overseen by the Nemesis crew.