The Master Spy is the Templar running a German spy network in London in 1916, and the final target of Lydia Frye's World War I memories in Assassin's Creed Syndicate. He also leads a small cult devoted to the Isu Juno, whom he calls his Beloved.
Lydia raids the carpenter's shop said to be his headquarters. He stuns her with a grenade and jumps through a window, and his men slow her down. She finds him again burning everything that could point to Juno and kills him.
He is a Sage, a reincarnation of Juno's husband Aita, whose memories had completely replaced his own personality. Juno uses Lydia's memories so that his pattern can be added to her own. Some of his followers survive him; one, Rufus Grosvenor, later chases the Koh-i-Noor.
Juno
Juno is the Isu who hijacks the Initiate's Helix session in Assassin's Creed Syndicate and sends them forward to 1916 to relive Lydia Frye's memories. Through that detour she tells her own story and tries to win the Initiate over.
Winston Churchill
Winston Churchill is Lydia Frye's contact in the 1916 World War I memories. He sends her after German spies in London, arranges an anti-aircraft boat against a dirigible raid, and supplies intelligence for the hunt for the Master Spy.
Lydia Frye
Lydia Frye is Jacob Frye's granddaughter and the playable Assassin in Assassin's Creed Syndicate's World War I memories, set in London in 1916. Working for Winston Churchill, she hunts a network of German spies and their leader, the Master Spy.
The Initiate
The Initiate is the player's own modern-day character in Assassin's Creed Syndicate: a Helix user working secretly for the Assassins. Bishop has you relive the genetic memories of Jacob and Evie Frye to find a Shroud of Eden, while you watch Shaun, Rebecca and Galina through camera drones.