SPOILER ALERT: The following story contains plot details from “Hello Goodbye,” the Season 4 finale of “Slow Horses.” “Slow Horses” is not, as a rule, a sentimental show. Deceptively disheveled spymaster Jackson Lamb’s (Gary Oldman) idea of caring for his “joes” is to negotiate up their active-duty death settlement on a bureaucratic technicality. Yet the […]