World War I is a bonus Helix simulation in Assassin's Creed Syndicate that drops you into London in 1916 as Lydia Frye, Jacob's granddaughter. You hunt a German spy ring for Winston Churchill across seven memories, while the Isu Juno speaks to you between them.
While you relive the Frye twins in 1868, a voice draws the Initiate to a rift in the Helix. Stepping into it moves you nearly fifty years forward into Lydia Frye's memories of wartime London, with zeppelins over the city and soldiers guarding the bridges.
Lydia grew up comfortable and at first wanted her studies more than the Brotherhood. Losing friends and relatives to the war with the Templars changed her mind, and Jacob and Evie trained her. She married fellow Assassin Sam Crowder just before the war; he enlisted, and she stayed in London to deal with German agents and the British Rite of the Templars.
The Darkest Hour opens the simulation at Tower Bridge. The Spy Hunts (The Apothecary Twins, The Magpie) follow, then the Spy Hideouts (Hopton's, Clarence Stock House, 17 Walpole Lane), and finally The Master Spy. Each hunt and hideout is a short, self-contained job.
After most memories, Juno cuts into the simulation to talk to the Initiate about the Isu: how they made humanity and how they failed to survive the Great Catastrophe. She also tries to win the Initiate over to her cause.
Lydia kills the Master Spy, who turns out to be a Sage devoted to Juno. Juno then thanks the Initiate for showing her what became of him and suggests she and the Assassins could work together one day.
Charles Darwin's London Stories
Charles Darwin's London Stories are side memories in which the naturalist, a friend of the twins since the Starrick's Soothing Syrup affair, asks for help as his enemies turn from argument to threats. You protect a fossil, destroy toxic flowers, tear down smear posters and finally rescue Darwin himself.
Charles Dickens's London Stories
Charles Dickens's London Stories are a set of side memories in which the novelist recruits Jacob and Evie Frye into the Ghost Club and sends them after rumours of demons, hauntings and spectral thieves around London. Most cases end with a human culprit behind the supposed ghost.
Epilogue
The Epilogue in Assassin's Creed Syndicate's memory list holds one memory, Pressed Flowers, where Evie collects flowers around London for Henry Green's herbarium. Collecting every pressed flower is also tied to the Language of Flowers achievement.
Karl Marx's London Stories
Karl Marx's London Stories are five side memories in which the exiled philosopher asks the Frye twins to help London's working people rather than the comfortable citizens they have already helped. You shield his union meetings from police spies, expose a dangerous factory, stop a grieving worker's bomb plot and guard a rally.