The premise of Slow Horses is too good to fail. A thriller about MI5 agents? Great. A thriller about subpar MI5 agents who’ve been relegated to the proverbial backup team, yet continue to find themselves in the line of fire? Even better. Throw in a drunken, irritable Gary Oldman as the head honcho, and you have yourself a hit. Which is what Slow Horses has been in its first two seasons and continues to be in its recently released third. The new installment introduces two characters, played by Sope Dirisu and Katherine Waterston, who quickly become embroiled in a murder and kidnapping affair. Little more can be said without spoiling the first few episodes. Just know that Jack Cartwright, Kadiff Kirwan, Aimee-Ffion Edwards, and Saskia Reeves—thankfully—reprise their roles. —Jack Sullivan