The emotional core of the episode is the secret Liz is carrying. Having been the one to tip off the police, she watches Reddington’s downfall with a mixture of cold calculation and lingering guilt.
This creates a tension between (punishing Red for his crimes) and utilitarian safety (keeping Red free to catch worse people). The episode asks: Is the world safer with the devil in a cage or the devil on a leash? 4. Red’s Resilience and Performance [S6E2] Public Enemy Number One
A breakdown of and his best lines.