Working for customs policeman Ash arrests drugs courier De Carlo and takes his place to meet the contact but the hand-over is bungled, Ash's colleague Tommy is crippled and Jago, a loose cannon who has killed De Carlo's actual buyer, escapes with the drugs. Facing dismissal Ash accepts an invitation from former boss Valerie to join the Unit, a new undercover agency she set up with a man called Cartwright, charged with arresting the big time drug peddlers. For Ash the hunt is personal but Jago also falls foul of Xavier and Docker, from whom he stole the drugs. Kim and Martin, two of Valerie's agents, locate Xavier, leading Ash to Jago but Cartwright is annoyed that Ash did not allow any of the pushers to point him towards the head of their drugs ring, a man called Roach. Written by don @ minifie-1

Whilst shadowing drugs dealer Xavier the team discovers that he is up against a rival gang led by a boy called Fitz. They are using adapted guns which are lethally unstable and claim a casualty. D.I. Gemmill tells Ash that somebody is flooding the capital with them and must be stopped. At the same time Tommy is concerned that Fitz may be involving young Cal, guardian of his little brother and sister whilst their mother is in hospital but Cartwright opposes the team showing its hand to Xavier as it would destroy the link to his boss. Cal makes his own luck and the team rounds up the gun peddlers but Roach still remains at large. Written by don @ minifie-1

Tommy picks up on the fact that Xavier is using a dry cleaners as base for a money laundering service and names one of its couriers as a man named Blair. He in turn deals with young Zubin Ray, whose shop-keeper father Tahir uses Hawala, a legitimate money transfer scheme which the boy exploits to enrich himself. Tommy visits the shop which is invaded by gunmen firing warning shots so the Unit members approach Astin, Zubin's respectable and disapproving older brother who is being leaned on by Reid, the 'Accountant' the fixer behind the scam; he is unhappy with Zubin's attempt to cross him and threatens Tahir and the shop. Ash does a deal with Astin which leads to Reid's demise though the Unit is still no closer to netting Roach. Written by don @ minifie-1

Continuing to stake out Xavier the team learns that Roach has a new drugs supplier, a handsome, street-wise Norwegian known as the Viking who is aware that the Unit's agents are following him and quick to give them the slip. Roach however begins to see him as a rival more than an ally. The team decides to get to the Viking through his girl-friend Mandy but it is Stacey, a former drug addict whom Ash has helped regain her child from social services' care and who agrees to go undercover for him who helps the team nab the Viking. Written by don @ minifie-1

Foolhardy thrill-seekers are dying from taking Sherberts, pills distributed by ex-rave DJ Scooter, who is not using the formula recommended by their manufacturer Marvin in order to make more money even though this makes them, more dangerous. Following the arrest of key pusher Carlos Scooter leans on young bridegroom to be Paulo, a pizza delivery boy in need of cash, to replace him. But when Paulo is involved in a road accident and hospitalized the Unit must get to him before Scooter, taking Paulo's pregnant girlfriend hostage, can silence him. Meanwhile Ash, working closely with D.I. Gemmill - in every sense - discovers that Cartwright's rivalry with her boss Stannard is part of a long-standing feud from when they were policemen together. Written by don @ minifie-1

The team learns that a violent thug nick-named Yorkie is arriving in London to work with Roach's crew and they follow him. Ash recognizes Yorkie's driver as Alex Price, an old friend before he turned bad and urges him to get out but Alex tells him that he is working off a financial debt to the villains and cannot run. Ash's wife Lorna reveals to Tommy her husband's old friendship and the team realizes that Ash is biased so Ash tries to counter by getting Alex to turn informer to Cartwright. Everything now depends upon whether Alex's information that Yorkie is about to rob a casino can be trusted or whether he is leading Ash into danger to save his own neck. Written by don @ minifie-1

Vicious young ex-con Justin Casby arrives in town, keen to move in on Roach's territory and killing one of his dealers to force a meeting with Roach himself. However Stannard's men raid most of Roach's distributors, including Xavier, to Cartwright's fury, forcing Roach to find another supplier and taking on board the manipulative Casby. Whilst the Unit learns who is relaying their information to the other side Ash, regarded as a true loose cannon by Cartwright, feels that he is now for the first time on the right road to unmasking Roach as the boss of the drug operation. Written by don @ minifie-1

Ash is frustrated when Cartwright tells him there is insufficient evidence to arrest Roach so Ash and Tommy bug Roach's office. However Casby discovers the bug and the expected drugs delivery turns out to be a booby-trapped decoy lorry - which kills a Unit member. An enraged Ash assumes a false business identity for a show-down with Roach, leading to a much-desired arrest and a slap in the face for Stannard. Written by don @ minifie-1