Secret Service follows senior MI6 officer, Kate Henderson, whose life must seem pretty ordinary to those who don't know her well, as she's happily married with two teenagers and a job in the civil service. 

However, Kate's real job is heading up the Russia Desk of the Secret Intelligence Service. When her undercover operations reveal alarming evidence that a senior UK politician is possibly a high-level Russian asset, Kate is in a race against time to uncover their identity.

Then a young woman is brutally murdered, throwing Kate and her team into the spotlight. With blood on her hands, her reputation to uphold, her family hanging by a thread, and an election looming, Kate is quickly running out of options and the clock is ticking….