This installment in the series takes place in 1868 London during the Industrial Revolution. It tells the story of two twin Assassins named Jacob and Evie Frye, who must fight the Templars in London in order to restore the Monarchy and the Church. Along the way, the Assassins team up with Charles Darwin, Charles Dickens, and Queen Victoria.
Templar Grand Master Crawford Starrick has destroyed the Assassin Brotherhood in London and has taken over the city. He plans to poison the city's population with a "soothing syrup" and assassinate the Prime Minister. It's up to the Frye twins to take down the Templars before they tear London apart, all while searching for another pesky Piece of Eden called the Shroud.
The Shroud has the power to heal all wounds and make you immortal. It also bestows superhuman strength. Naturally, that's exactly what Starrick wants. The Frye twins work together to take down Starrick and recover the Shroud.
Meanwhile, in the present timeline, the Assassins are on a mission to find the Shroud before Abstergo does, and get into a bit of trouble along the way. They also discover that Juno has been manipulating Abstergo all along and has her own plans for the Shroud, which remain unclear...