When Gene interviews a witness to an armed robbery, alarm bells start ringing. He suspects Chas Cale, a renowned criminal from his Manchester days is involved.

Chas is brought in for questioning but admits his adrenalin-fuelled life of crime is over as he is now too ill. This news makes Gene question whether he is also getting past his prime.

Ray and Chris are sent undercover to a local pub to get more clues, but find themselves distracted by a brand new computer game - Space Invaders.

They eventually come up trumps when they track down a suspect, Billy Dane. But to the team's frustration, Billy has a water-tight alibi. The trail turns cold until Billy's body is found on wasteland and his seven-year-old nephew Donny is the only witness.

Alex puts her own life in danger when she goes to question the murder suspect and it's up to Gene to muster all the strength in his old bones to save her.