DI Carl Harrington heads ESUS on his first case: pursuing suspected drug importer Lance Anthony Izzard. A crash caused by an overtaking vehicle near roadworks kills the tanker's driver and co-driver.

ESUS backs up DS Barbara Hall, undercover for 6 months, suspected of aiding drug importer Miguel Morena. When Hall disappears upon arrival at London's City Airport, suspicions arise: has she gone rogue with Morena or fallen for his associate?

When Hall is murdered, DI Brown is determined to prove that Dt. Supt Hughes was somehow involved.

When junior secretary Peter Gleeson commits suicide after being exposed as being a homosexual, the team go undercover to investigate a private drinking club called the Golden Goose where they become embroiled in scandal, blackmail and tragedy.

Owner Pauline Monroe's sidelines in drugs and prostitution appear to be the key to unraveling the entire scam, but Hughes and McEwan come close to becoming embroiled themselves. As Edna discovers the truth, tragedy strikes when a drunken Monroe unleashes a gun on DI Brown.

DS Harper comes face-to-face with an old adversary when Frankie Li goes undercover as a martial arts expert as the team investigates a corrupt Hong Kong businessman.