Critical Incident Season 4 is to Premiere on BBC One

Officers from Merseyside Police attempt a dangerous rescue when a car gets stuck in the River Mersey with the driver trapped inside. Firefighters in Newcastle and Humberside are out on shift in the days leading up to Bonfire Night, the most dangerous time of the year. And two police officers are shocked by a nasty assault in Poole.

Kent Police officers risk their lives to rescue an individual trapped on a cliff face. West Midlands police track down a man in possession of a gun, and how man's best friend came to play an essential role in British policing, tracking down criminals and protecting their handlers.

The Covid-19 pandemic brings fresh dangers for emergency service workers all over the UK, including a surge in coughing attacks on police officers. Also, how groundbreaking research into the psychology of crowds could help prevent attacks on police.

A Critical Incident special looking at knife crime in the UK, including a dedicated police task force in Essex and a groundbreaking scheme in the West Midlands.

A Critical Incident special exploring what it takes to police Britain's roads, including a Metropolitan Police operation to tackle moped-enabled crime.

A PCSO and his colleague are attacked as they try to arrest a man suspected of a spate of burglaries at Christmas.

A former policeman from Northern Ireland rebuilds his life after losing both arms in a rocket attack on his vehicle. In Leeds, a patient threatens a paramedic with a 12-inch knife, and a Humberside police officer is determined to get back on the beat after a stay at the Police Treatment Centre.

A police officer shot at close range is in danger of losing his sight, and a speeding motorcyclist is pursued through London.

Two life-changing assaults cost a police officer his career and have a huge impact on his health as he is diagnosed with complex PTSD. In Kent, the drugs and gangs team are out on a raid, tackling the growing drug problem in their county.

A rural village becomes the scene of a violent gun fight when a firearms team confronts an armed man.

In Ashford, a report of a burglary ends with a police officer fighting a man armed with a knife. A dog handler with West Midlands Police is impaled on a spiked fence as he and his four-legged colleague chase down a suspected thief, and Kent Police officers get to grips with taser training.

Firefighters in Newcastle and Humberside are out on shift in the days leading up to Bonfire Night, the most dangerous time of the year.

In Humberside, firefighters are shocked when they are attacked by the residents of a buring house as they try to put out the flames.

A shocking discovery by two unarmed police officers brings a bomb disposal unity to a leafy suburb of Merseyside.

In Essex, police officers are doused in petrol and threatened with being set alight when a moped chase ends in chaos.

In Staffordshire, PC Claire Bond is left with life-changing injuries after a high-speed car chase ends with a criminal driver mowing her down. With both legs crushed and broken, Claire is forced to give up frontline policing for over a year – but grit and determination get her back on her feet. Elsewhere, a paramedic is kicked to the floor by a patient she's trying to help, and a police officer is scratched and spat at as she tries to make an arrest.

In Cumbria, a police officer is mowed down by joyriders travelling at over 50mph. But despite his serious injuries – including losing an arm – Inspector Jon Sherlock is determined to get back on the beat. PCs Laura Jew and Rich Chant are patrolling Birmingham city centre when an unprovoked attack sees Laura strangled and Rich's nose broken. With the offender's hands around her neck Laura fears for her life as she waits for back-up to arrive. And paramedic Suki Kaur is left traumatised after a nasty racial attack by a patient.

In Great Yarmouth an undercover cop chasing down county lines drugs dealers is dragged along the road by a car as he tries to apprehend the driver. In York there's a shock discovery for PC Rich Farrar as CCTV reveals that the suspected bike thief he just arrested was carrying a large kitchen knife, and a paramedic who helped patients in the aftermath of the 7/7 bombings is violently attacked by a patient.

A paramedic couple face their worst nightmare when the wife hears over the radio that her husband has been attacked and knocked unconscious by a patient.The Manchester Tactical Vehicles Unit put their lives in danger daily as they target vehicle crime using high performance undercover cars, and terrifying bodycam footage shows the moment a female police officer has chunks of her hair ripped out by the son of a man she's trying to arrest.

A paramedic whose ambulance already had patients on board stops to assist in a road traffic accident. But as he tries to treat one of the people involved, he's headbutted so hard he's knocked unconscious. A rookie police officer experiences the darker side of the job when he is attacked by a patient he's guarding in hospital, a police officer has his finger badly bitten as he tries to stop a criminal, and shocking bodycam footage reveals the moment a police officer has his finger badly bitten as he tries to stop a criminal from spitting at him.

In Bedfordshire, PC Hayley Robinson has her ankle crushed after being driven at by a criminal in a car. But after five months of treatment she's ready to go back to work. Elsewhere, fire crews across the country prepare for Bonfire Night – the worst night of the year for violent attacks on firefighters. And Saturday night revelry ends with a police officer needing stitches after an unprovoked attack as the clubs and bars kick out.

A detective has a chemical thrown in her face as she tries to apprehend a gang of burglars, a police officer is injured as he tries to arrest a man who is threatening to kill officers with a machete, and a paramedic is headbutted by a patient.

In Edinburgh, PC Fraser Bell severs his artery while trying to restrain a youth, but his quick-thinking colleague saves his life by stemming the blood flow. In Manchester, PC Ian Bruce is part of a specialist team tackling vehicle crime. It's a dangerous job, often involving high speed chases, and Ian finds himself alone and vulnerable as a gang he's chasing go on the attack, using their car as a weapon. And paramedic Jodie Nutley-West is shocked when a patient suddenly lashes out.

In Wiltshire, an officer fears for his life when a drunk man turns violent and threatens to kill him. The terrifying ordeal lasts for nearly 20 minutes as PC Mat Baker waits for backup to arrive. Elsewhere, a burglar deliberately drives straight at an officer who is trying to arrest him, breaking his leg, and a paramedic is attacked by a man after she refuses to give him a lift home.

In Hartlepool, PC Mick Johnson is stabbed in the arm as he attends reports of a man behaving strangely at a local convenience store. The shopkeeper is trapped inside with the knifeman, so Mick heads in to get her to safety.
Elsewhere, a policewoman is mown down by a driver trying to resist arrest, but she fights to get back on the beat. And a firefighter has his final round of surgery following ten years of treatment after a brick thrown through his window broke his nose in 11 places.