In its second season, titled “Dead Lions,” the series follows the disgraced MI5 agents of Slough House as they are plunged into a new espionage crisis. The central case involves the suspicious death of a retired “slow horse” named Dickie Bow, who dies on a bus shortly after sending a cryptic text about a mysterious Russian operative from the Cold War known as “cicadas.”
The team, led by the slovenly and brilliant Jackson Lamb, begins investigating. River Cartwright goes undercover at an upscale country retreat, posing as a journalist to infiltrate a group of wealthy Russian oligarchs and their hangers-on. He is trying to uncover a potential sleeper agent network being activated. Meanwhile, other agents like Shirley Dander and Marcus Longridge dig into the financial dealings connected to the case.
The season deepens the characters’ backstories and relationships. We learn more about Lamb’s painful history in Berlin and his connection to the original “cicada” operation. Louisa Guy struggles with the traumatic death of her partner, Min Harper, from the first season. The personal and professional often clash, creating emotional tensions within the team.
The plot reveals a complex conspiracy orchestrated by a former MI5 agent, James “Judd” Webb, who is now working with Russian interests. His plan involves framing River’s father for treason and manipulating events to destabilize British intelligence. The action culminates in a tense standoff at a secure data farm, where Lamb and his team must stop Webb from leaking sensitive information.
Despite their bungling reputations, the slow horses ultimately prove their worth through grit, unconventional methods, and loyalty to one another. They manage to thwart the plot, though often in messy and unofficial ways that require Lamb’s expert covering of tracks. The season ends with the team still in exile at Slough House, but with a slightly renewed sense of purpose, having once again cleaned up a mess that “the Park,” MI5’s headquarters, could not handle.