Giles Nunn and Carrie Selhurst are an upper crust couple who, partly for kicks and for the profits, commit highway robbery in lonely country lanes, along with the lower class boy Tommy Garret, whose dad is a friend of George Carter. Regan is on to them and Carrie gets arrested, but her unwillingness to cooperate leads to the death of the next victim.
A masked gang robs a security van and Carter's informant names ex-soldier Tober as its leader. Regan trails the gang to their junk shop hide-out where they plot their next heist for their client, a German political terrorist. The Secret Service has one of their men infiltrating the gang and Regan is told to back off arresting them so as not to blow his cover. Regan, however, is his own boss and goes ahead with the ambush.
Joey Stickley, Regan's informant, is greedy but generally reliable. With Haskins in Toronto, his stand-in, Quirk, is obsessed with catching the 'Post Office Gang' and his grass tells him they are about to rob a jeweller's shop. Carter goes undercover as a driver and meets Stickley, one of the gang, on the dummy run, but, come the actual robbery, Stickley has been replaced by Quirk's informant, to whom he has fed wrong information, in order to settle an old score with Quirk. As a consequence, the police operation is a failure.
Suspect Andy Deacon collapses whilst Regan is interviewing him and a doctor claims that his injuries were caused by an assault. Whilst Regan never touched him, he is suspected of giving the lad a kicking. Deacon's dangerous older brother Phil puts out a hit on Regan, whilst muck-raking journalist John Frewin also tries to expose him in the local press. Regan and Carter must find the man who really hospitalized Andy Deacon before it is too late, though Regan's new lady-friend, a probation officer, is able to help.
Carter's school-teacher wife Alison is deliberately killed by a hit and run driver whilst posting his football pools. Alison had actually borrowed a coat from Judy, the French mistress, who consequently goes on the run as it was clear that she was the intended victim. On her trips to France with her class she had become involved with a gang for whom she would smuggle goods but has made it clear that she wanted out, hence the attempt to silence her. Regan has to find her before Crofts, the gang boss, gets to her.
Five years earlier Regan got promotion following the Golden Maid dairy robbery, thanks to a tip-off from Noah Riley. Now a reporter, Thomas, has got Noah and offers him money for his elderly mother if he will claim Regan acted illegally in order to discredit him. Regan's efforts to find Noah and prove conspiracy without telling Haskins put him in danger of suspension and Noah's mother in danger from the dairy robbers. Perhaps mini-cab boss Manny Bellow can come up with helpful information.
Colin MacGruder and Ray Stackpole, two Australians with the theme "Nice 'n' easy does it", commit eleven armed robberies, in each case stealing Kruger Rands purchased from the same firm, the managing director's secretary tipping them off as to the whereabouts of the coins. They also pay an informant to make it look as if Haskins is taking a bribe and plant money in his greenhouse, so that he is suspended. Regan traces the Kruger Rand connection but all the villains escape. However, the absence of witnesses means that Haskins is completely exonerated and reinstated.
Vic Labbett, a violent robber who fled England following a robbery, has now returned from exile but only temporarily. His aim is to pick up the cash from the heist and convert it into diamonds and fly out of the country again. Regan is on to him and although Labbett initially eludes him, a muddy car chase across the air-field leads to his downfall.
Two young villains, Tyson and Jenner, working for gang boss Tony Kirby, are relieved of the spoils of their robbery by a mysterious gun-man, who shoots Jenner in the leg. Nobody knows who he is until Regan has a word with Jenner's disgruntled father-in-law, which leads to a shoot-out in a theatre. At the same time Regan is made a tempting offer to go into private security work.
Australian villains Colin MacGruder and Ray Stackpole return to London and steal a bus, posing as its crew. They rob an art dealer travelling on the bus of a Goya painting, which they plan to sell to a buyer in Amsterdam. Regan tracks them down by leaning on their accomplice, the dealer's female assistant, leading to a river chase and a shoot-out, making it the end of the line for the boys from Down Under.
Informant Popeye is abducted by villain Maynard whilst staking out small-time crook Frankie Little after a jewel theft. Regan pulls Little but agrees to drop charges if Little will go ahead as planned, acting as Maynard's driver on an upcoming robbery. However, all Little is able to phone in to Regan on the eve of the heist is "Old Readies". Regan must locate where the crime will take place before it is too late for Popeye.
An armed gang kidnap telephone engineer Ronald Peters and hold him in an empty house, using his expertise to trigger off false alarms in some banks, diverting the police whilst the gang rob alarm-free premises. Regan is initially resentful when college graduate Sergeant David Keel, a telecommunications expert from Bristol CID, is drafted in to help, but comes to respect his knowledge and his bravery in catching the gang.
The day before the start of a new term, the university branch of the National Mercian bank is robbed. Regan and his squad arrive and catch or shoot most of the gang but known killer Wands and simple side-kick Monks are still inside with the manager and two women hostages. Haskins' hesitancy in ordering the police marksmen to fire on the robbers leads to a car chase and fatalities, causing Regan to round on his boss.