When Mary finds herself in a public scandal and the family faces financial trouble, the household grapples with the threat of social disgrace. The Crawleys must embrace change with the next generation leading Downton Abbey into the future.

Power is up for grabs as two warring crime families clash in a battle that threatens to topple empires. In the crossfire stands Harry Da Souza, a street-smart 'fixer' who knows too well where loyalties lie when opposing forces collide.