Netflix has greenlit a new U.K. drama from “The Gold” showrunner Neil Forsyth based on a jaw-dropping true story about a bunch of Customs employees who went undercover to infiltrate some of Britain’s most dangerous drug gangs.

Titled “Legends,” the six-part series follows a thrilling criminal investigation based on Forsyth’s extensive research and interviews with those involved.

“In the early 1990s, at the height of the international war on drugs, the government agency in charge of Britain’s borders, Her Majesty’s Customs and Excise, realized that they were losing the battle against drug smuggling. Their solution was extraordinary,” reads the logline. “In a top-secret operation, a small team of British Customs employees were sent undercover. Their task – to infiltrate Britain’s most dangerous drug gangs.”

“They were not trained spies. These were ordinary men and women, plucked from ordinary lives around the U.K, put through...