It's the winter of 2019, and the airport is having its busiest year to date. This is Heathrow before lockdown, where the Aviation Police are on the front line to protect Heathrow, and officers Terry and Dave return.

Returning to Britain's busiest airport with the familiar face of airside officer Ian, who has a close shave out on the runway. Veteran Border Force officers Glen and Amarjit hunt down smuggled cargo, and there's a new engineering kid on the block.

It's a day like no other, with one octogenarian forcing herself into the country under the watchful eye of Passenger Experience Guru Demi. Terminal 4 turns blue, and airside Hugh has a potential environmental mess on his hands.

Heathrow's heroes deal with the UK's worst winter storms. Whilst winds rage out on the airfield, and safety officer Rachel with airside Ian go into battle with bins and royal birds, inside the terminal there's a bad smell in immigration.

Border Force Kat decides whether to allow a holiday-maker arriving with little money and a confusing story into the UK. Meanwhile in Terminal 3, meticulous Customer Service Agent Mr Sho is having issues with a 400-year-old Japanese tradition.

In the coloured lanes of customs and excise, we rummage through carry-on luggage on the lookout for secret stashes. Virgin Atlantic's punctuality record is put in jeopardy by a captain's bottle of water, and there is love, actually in the air.

It's all upgrades and upper class at Heathrow as Virgin's clubhouse manager Holly showers passengers with her VIP treatment Valentine-style, while officers Terry and Dave have to deal with an unhappy upgraded passenger.

At Britain's busiest border, officers Kat and Tracy help a student from India who's arrived with no fixed abode, while on the airfield, Airside Ian is ducking and diving on the runway. Terminal 4 welcomes an exuberant new ambassador.

At Heathrow's Terminal Four, new airline on the block Vietnam Airlines are battling baggage woes in the lead up to the holiday period. Rookie engineer Mo comes up with an ingenious solution to ensure no-one is stranded abroad without their luggage.

It's all smells at Heathrow's Terminal 3 with a new restaurant, and Border Force dog Jessie sniffing out thousands of pounds. Meanwhile, Airside Ian is ramping up his crow impersonations, and Demi prevents a cardiologist having a heart attack.

Answering the question of whether you could pick up someone else's boarding card and take a trip around the world. Plus, some plane-spotters await a rather rare sight.

There's something smelly in Cargo that Border Force have to get to the bottom of. Passenger Experience Manager Harry rushes to a gate that's had its door smashed in and King of Terminal 2 Demi has 700 passengers descend on him - one being a pop star.