The episode opens with a high-stakes training mission at Stansted Airport. Agent River Cartwright (played by Jack Lowden) is tasked with stopping a suspected bomber but receives conflicting descriptions of the target's clothing from his supervisor. Despite his instincts, River follows the order, allowing the real "bomber" to trigger a simulated explosion.

The show is also available for direct streaming and replay on CANAL+ in France.

Following this public and embarrassing failure, River is demoted to Slough House . There, he and other "slow horses" perform mind-numbing tasks like sifting through trash and transcribing phone calls.

The status quo is disrupted when a young man is kidnapped by a far-right group that threatens to behead him on a live stream, drawing the "slow horses" into a real-world conspiracy. Viewing Information for France