Jack the Ripper (DLC)

Jack the Ripper is a single-player downloadable content addition for Assassin's Creed: Syndicate and will be released sometime in December 2015.

Official synopsis
20 years after the events of Assassin's Creed Syndicate, 'Jack the Ripper' has embarked on a brutal reign of terror that shocks London to its core and threatens the very existence of the Brotherhood of Assassins.

Reference
Assassin's Creed Syndicate Season Pass - Jack The Ripper