Nursing his terminally-ill wife, Det Insp Jack Frosts life becomes more stressed when, during a missing-child investigation, he unearths evidence on a 30-year-old case involving a skeleton chained to a locked strongbox that turns out to be empty.
Frost investigates the murder of a teenage girl, and the case of a woman who has been receiving threatening phone calls. Meanwhile, at the Denton police station, there are threats, deaths, arson and a staff shortage.
Frost investigates an MPs son who is involved in a hit-and-run accident, and a robbery at a private casino, which occur on the same night. He gets a humorless new partner to assist him.
When Frost learns the identity of Natalie's son, he's sure he has found his murderer. Frost also links Natalie's boyfriend, Aspinall, to the robberies but doesn't know where to find him.
Frost learns both victims belonged to the same seniors club and were driven to and from the club by volunteer drivers. Frost seems to have it in for Roy, one of the drivers.
Jack is called out to deal with the accidental death of a known drug addict, and finds himself teamed up with a new Detective Constable who has an attitude problem after being demoted from Inspector for assaulting a superior officer. The case takes a surprising turn when the post-mortem reveals the deceased was actually battered to death.
In an effort to catch the rapist, Frost jeopardizes the safety of a junior female officer.
Frost leads an investigation into the disappearance of a six-year-old girl. His only suspect is a Down's syndrome sufferer who has a secret he will not reveal.
When a young animal rights protester is seriously injured at a meeting of the local hunt club and dies in hospital, Frost's only suspect is quickly ruled out when another body is discovered.
While Adie clings to life in the hospital, his teammates, Paul and Jamie, receive threats, and Frost believes they are related to a corrupt business deal the three soccer players were involved in. The case of the unidentified driver grows more mysterious.
Boxley disappears after his hideaway is firebombed. Frost rounds up all the suspects in the robbery. Boxley turns up but is still in danger. It turns out Boxley was having an affair with his son's girlfriend.
A fire leaves Frost homeless just as he's given a kidnapping case. With nowhere else to go, he sets up a 24-hour operation at the home of the victim's sister, who received the ransom demand. The case drags on: a likely suspect is found murdered, and the ransom demand escalates.
During a very busy day, Frost defuses a hostage situation in which he's the hostage. Then he learns of a soldier who was shot dead during an exercise. The army refuses to let him investigate because it is outside his jurisdiction, but Frost persists. Meanwhile, an armed robbery case is a distraction.
A naked woman commits suicide by throwing herself from the roof of Denton Church. When the body of the woman's lover is found the next day, Inspector Frost's investigation uncovers a male escort service.
A physiotherapist is found with her throat slashed in a busy car park. Police have little go on until Frost looks in the victim's electronic organizer, where he finds the name of a religious author and pillar of the local church. At first the writer denies knowing the woman, but Frost confronts him with love letters exposing an affair with the victim.
Frost still believes his instincts are right in the knifing case, but is forced to release his prime suspects after a run-in with their solicitor. Those same instincts lead him to a breakthrough in the assault case at the university.
A ruthless kidnapper holds a supermarket chain to ransom by threatening the life of a young boy.
Dour DI Jack Frost suspects a man he arrested years before for a series of bizarre assaults on children could have returned to the area and recommenced his unsavory activities. He tracks down the culprit, who swears he's turned over a new leaf, and decides not to charge him.
Frost is suspended from duty when his quest for the truth in the case of two wealthy brothers accused of murder goes too far. Meanwhile, a new lady friend enters his life.
The inspector investigates two domestic cases: one tragically straightforward, the other cruelly deceptive.
Overwhelmed with grief at the death of a colleague, Frost tenders his resignation. But Superintendent Mullett maneuvers Frost back into service. Hazel Wallace, formerly a uniformed woman police constable, is now a full DC responsible for investigating the suspicious death of a reclusive art collector.
Frost becomes embroiled in the death of a runaway teenager found drowned in the Denton River. A health officer who was investigating illegal practices at a meat-processing plant goes missing and his body washes up down river. Meanwhile, the inspector returns to his refurbished house, and to pay off his bills takes in a lodger.
Frost investigates an attempted armed robbery at a local brewery and comes face to face with an old adversary. His new partner, DS "Razor" Sharpe, is called to the scene of a hit-and-run where a woman is critically injured. Forensic evidence reveals the hit-and-run was not an accident. The subsequent investigation into the life of the victim leads to tragedy. A stakeout at the brewery ends in a violent chase.
Frost faces off against an old enemy, a lawyer named Warrinder. Round one goes to the solicitor when the inspector takes things a little too far in the interrogation of a drug dealer represented by Warrinder. Frost is partnered with the "by-the-book" Sgt. Dorridge. Meanwhile, a con artist tries to steal a vacationing Supt. Mullet's car.
When a local power station worker falls to his death after he has robbed and then a young detective is murdered and Frost wonders if it is related to the investigation he was working on before his death.
As Frost works to identify the detective's killer things become more complicated as he must deal with a bizarre series of pet shootings. He must enlist the help from a computer system run by a junior WPC.
Denton’s female population must look out for a con man that has been posing as Frost. Frost is made to work with a soon to be wash out who has drug problems to work out why a women was killed by the railroad and then a surgeon turns up dead.
Frost has solved the railroad murder and must come to terms with having a daughter that he never knew he had. Det. Reid is found nearly dead in a public toilet after looking for contraband cigarettes. Frost still must solve the murder of the surgeon.
A body with no identification is found in a local reservoir, and a couple fall victim to a brutal killer in their own home. Frost is assigned a new, female, West Indian detective constable, Ronni Lonnegan, and gets off to a bad start with a few racially insensitive remarks. He then reluctantly accepts the help of a psychological profiler, psychiatrist Pam Hartley, who he met at a conference. Meanwhile, there is an inspection of Denton Police underway, and Frost's old-fashioned methods are not endearing him to the inspector, so Supt Mullett is forced to give him more support than usual.
Background enquiries turn up two previous deaths, which appear related to the case. But their initial suspect, armed bank-robber Charlie Lehman, turns out to have died in prison over a year earlier. As they work to profile the killer they are hunting, Frost starts to get close to Hartley personally as well as professionally, though neither realizes just how closely she is linked to the case until it is almost too late. Frost has a race against time to find where she is being held.
A vital witness to a gangland killing goes missing before she can give evidence in court, And frost finds himself under pressure to find her and her son before a hit man can get to them. Frost thinks he has won the lottery but he has lost his ticket!
When Denton's last quarry is vandalized and bodies start showing up, Frost becomes suspicious when the only witness in an autistic boy. When Frost finds a baby in his office he is confused, but he is then delighted when he learns it belongs to DS Hazel Wallace. Meanwhile more bodies keep showing up at the Quarry. Will Frost be able to find the person responsible before more people die?
Frost remembers a clue and dashes out of his promotion interview. Meanwhile, the prime suspect tries to provoke Reid to hit him so he can sue the police, but it's Frost's emotions that eventually get the better of him.
Frost returns to duty after his suspension for attacking a child killer. His first case is to identify a man found in floating in the canal. And a body is found with the right foot hacked off and replaced with a left. Frost discovers that the man with two left feet was passionate about ballroom dancing.
Frost's efforts to boost his stamina by joining a gym are interrupted when his workload piles up. The body of a man is found atop a mountain of glass at a recycling plant with little to identify him. And a businessman is caught in an embarrassing situation by his daughter's best friend who uses the opportunity get money out of him.
Frost discovers the dead man's wife has been seeing a hypnotherapist. The tragic affair with the businessman and the young lady seems linked to stolen passports and illegal immigrants from Poland.
Frost's trusted colleague, DS George Toolan, is critically injured through what may have been carelessness on Frost's part. The inspector's troubles increase when the local priest is found at the scene of a ritualistic murder, covered in the victim's blood. Evidence suggests the murderer's latest killing is a direct challenge to the police and to Frost in particular. With the clock ticking, Frost takes a gamble and puts his own life in jeopardy to corner the killer.
Frost and the team investigate the case of a person who has been missing for twenty years when the case is re-opened after the remains of a teenage girl's body are found.
Frost isn't happy when he has to work with DS Marsh after they have clashed in the past. They try to put the past behind them when they investigate the kidnapping of a bus driver and his conductress. They also look at the murder of children's entertainer.
After three naked male bodies are found buried in the form of a triangle, Frost and the team investigate if it is part of a satanic ritual.