Smithy's caught in a gun-smuggling plot

DC Jacob Banks finds himself literally looking down the barrel of gun when a terrified young boy Emile Grover attempts to hand over the weapon without pulling the trigger. When Emile is questioned, he admits he was looking after the gun for Andre Tyrell, who claims he can smuggle British army weapons from Iraq in Sun Hill. Elsewhere, it's Pc Mel Ryder's first day, and she attends a break-in with Sergeant Smith, where Sarah Figgis claims her ex-husband Billy has trashed the place. Smithy and Mel trace Billy to a hostel, where the ex-soldier has been awarded for bravery. But after pulling a gun on the officers and handcuffing them together, Billy makes a runs for it. Later, Sarah tells Smithy and Mel that her son, Josh, has gone missing and she is certain that Billy has taken him. A horrified Billy swears he has nothing to do with Josh's disappearance but admits he's been smuggling guns for Tyrell. When is Emile also reported missing, officers realise that Tyrell has both boys. Can they get to them in time?