Police dogs Meg and Thor reunite with their handler after three months, and their first mission is to track a car that's linked to drug dealing. Sniffer dog Billy searches a graveyard for a stashed gun.

Rookie German shepherd Kane and his handler pursue a driver who's fled on foot and a burglar targeting the elderly. Then explosives detection dog Oscar is called to a bomb scare in central London with his new-to-the-job handler.

Newbie Chico sniffs out an enormous cannabis stash and disrupts a major drug operation.

German shepherd Thor joins a firearms unit as his colleague sniffer dog Meg goes on a drug raid. Meanwhile, a fire investigator and his dog Dexter discover whether suspicious fires could be arson.

Dog Patto is injured chasing a burglar, and whether he can return to work hangs in the balance.

Chico confronts an armed man, and sniffer dog Lucy checks out a suspicious food delivery driver.