When young soldier Mark Blakefield takes his own life at the Hillsdon Army Base, his friends and colleagues believe the suicide was caused by the traumatic experience of watching his friend, Danny Ferris, die in battle. However, evidence soon comes to light that just before the death, Mark was seen arguing with his superior, Lieutenant Lockfield. When the body of a young female is pulled from a nearby river, it turns out to be Mark's girlfriend, Catz. A suicide note is soon found, claiming that she couldn't cope following her husband's death, and therefore had to take her own life. However, when Nikki discovers that Catz was having an affair with Lieutenant Lockfield, she suspects foul play. Things take an even scarier turn by Lockfield is mysteriously shot at close range. Meanwhile, Harry carries out the postmortem on Mark, and soon discovers he did not commit suicide, and was instead murdered by a blow to the back of the head. When Nikki discovers Catz made a phone call to Lockfield just before her death, she believes it could be the clue to catching him. A search of Catz' flat, however, suggests not only where she having an affair with Lockfield behind Mark's back, she had also secretly been dating his best friend Danny. Later, the police catch a man skulking at Catz' flat. Dennis Croft, a former soldier cashiered for drug peddling, claims that there was a cover-up over Danny's death, and that he was, in fact, killed by Lockfield after he found out he was seeing Catz. He also claims Mark found out about this, and that it was the subject of the argument they were having shortly before his death. CCTV evidence, however, discovers that Catz' death was due to a bizarre accident, so who would have reason to kill Lockford?