DS John Corbett

John Corbett turns up in the middle of a dangerous undercover job, embedded so deep inside an organised crime outfit that no one — least of all the audience — is quite sure where his loyalties sit. He's watchful, weathered, quietly charismatic, and draws DI Kate Fleming into an entanglement that blurs the line between cover story and something real.

Stephen Graham plays him at a low simmer, all coiled stillness and unreadable eyes, so that every scene carries a low hum of risk — is this a good man doing terrible work, or something else entirely? The show withholds answers just long enough to make you lean in, and Graham makes the not-knowing feel dangerous rather than gimmicky.