Corporal Gordon House is deployed to Afghanistan with a smart new pistol called the Glock 17. Nick believes that he needs to try and prove to him tjhat he can pass a weapons-handling test and get himself one. Things don't go to plan though. Simon attempts to gain the respect of others by studying Sun Tzu's Art Of War, landing Bird in trouble after she becomes drawn into his obsession.
After a blast from Nick’s past shows up, it throws him off his game which sees also has a dangerous effect on the rest of the team.
Nick wants some downtime so that he can focus on making a forensic profile of the Taliban bomber, but his team are constantly bugging him. He is over the moon to discover a disused roof terrace. but soon sombody else is also wanting to use the space. Towerblock comes up with a plan to scare Bird with Rocket's new pet rat.
After Mac and Rocket set fire to the Det, Nick ends up decding to take the blame and is forced to look after a Government Minister who is visiting the base as his punishment. He soon regrets asking Mary to look after him after she unexpectedly takes a liking to him.
Bird takes action when he's fed up of hearing about Mary from Nick. Simon tries proving himself on a computer game. Towerblock pimps the Lt Colonel's car out.