Gasforth's new bypass is causing problems for Fowler as his girlfriend Patricia has taken a fortnight's leave to join the protesters and he and his officers have to "enforce the law". When they arrive PC Goody falls for one of the protesters and decides to save the planet. Meanwhile, Patricia is rescued by the "green avenger".

A controversial bypass is under construction around Gasforth and a group of environmentalist protestors have set up camp in an area of woodland that needs clearing. Much to Fowler's disbelief, Patricia takes a fortnight's holiday in order to join them in the rooftops.

Matters are made more awkward for Raymond when he finds his men are required to clear the protestors during Patricia's stay, and he's far from amused to receive a letter informing him that MI5 have infiltrated the group. Grim, however, is far more concerned by a 'ding' received in his beloved, shiny Nissan Micra. He is, after all, an excellent driver himself...

Fowler and his men head out to the protest site, where he eventually finds Patricia sat on a treetop platform. She refuses and cries 'police brutality', to which a large, muscled man called Stallion - aka the Green Avenger - swings in to her rescue. Incapacitating Raymond, he and Patricia make a hasty retreat to his own sleeping space.

Left alone for another night and having seen Sergeant Dawkins disappear with Stalion, Raymond begins feeling bad about having dismissed her beliefs and principles. The next morning he heads back to the camp alone with breakfast in order to make peace. When he arrives, however, Stallion is inciting violence amongst the other relative passive protestors, and Patricia attempting to arrest him. A fight looks certain, but with a little distraction they overpower and arrest him.

Back at the station, Fowler announces to a stunned Patricia that Stallion has been freed. He is in fact the undercover MI5 agent, Carlton. Dawkins is furious, but Raymond is powerless. However, it becomes quickly apparent that it is neither Fowler nor Dawkins who the suave spy has issue with.