Watch Dogs: Legion: Walkthrough & Boss Guide

This is a condensed story overview of Watch Dogs: Legion (Ubisoft Toronto, October 2020), not a mission-by-mission walkthrough. The eight chapters and their mission names follow Shacknews and GamePressure; the story outcomes follow Wikipedia. Mission-specific tactics and puzzle solutions are not covered because they could not be verified. Spoilers follow.

In Wikipedia's plot, DedSec's London branch is led by Sabine Brandt and the AI Bagley. After Zero Day's bombings, Sabine shuts Bagley down and goes into hiding, the government hires the private military company Albion, and DedSec is blamed. Sabine later returns after finding a recruit through ctOS, and the group reactivates its safehouse and Bagley, then recruits more members and liberates London's boroughs. Missions after the Operation Westminster prologue are DedSec from the Ashes (Restart DedSec in some lists), Light a Spark, Clarion Call, Reporting for Duty and Digging Up the Past.

The Kelley chapter's missions are Lost in the Process, Clan Kelley's New Export and Bloody Mary Kelley. Clan Kelley is the criminal syndicate led by Mary Kelley, who, per Wikipedia, traffics people from Albion's deportation centres and was involved in the bombings.

The first Albion chapter's missions are Gap in the Armor, Inside Albion, Stealing Schemes and In the Belly of the Beast. Albion is the private military company that enforces the law without political oversight and, with ctOS and SIRS, turns London into a surveillance state (Wikipedia). Its CEO is Nigel Cass.

The 404 chapter's missions are Initiate Sequence, 404 Not Found, Coming Home and Into the Void. Wikipedia says DedSec uncovers that Skye Larsen, CEO of Broca Tech (Bagley's creator), runs experiments to turn human minds into AI programs, and then deals with her. The mission lists used here do not say which mission covers that confrontation, and this page does not describe terminal choices.

SIRS is the merged British intelligence agency. The chapter's eight missions are The Whistleblower, Espionage 101, Honey Trap, Hunting Zero Day, Smoking Gun, Kill Box, The Malik Dossier and Barbarians at the Gate. Per Wikipedia, Richard Malik, a SIRS whistleblower, asks DedSec to prove that SIRS leader Emma Child was behind the bombings, but he was actually trying to take control of SIRS and kills Child in an explosion that DedSec is framed for.

The second Kelley chapter's missions are Crashing the Auction, Market Closing and Falling From Grace. Wikipedia's plot says DedSec infiltrates a slave auction run by Kelley and learns she helped Zero Day smuggle explosives into the country. Kelley is expected to walk free, so DedSec leaves her to be killed by her former captives; she is not arrested by Detective Lau.

The second Albion chapter's missions are Restoking the Fire, Nigel's Close Shave, Defanging the Flock, #JusticeforLaClaire and London's Prospectors. Per Wikipedia, DedSec sabotages Cass's "Project THEMIS" combat-drone army and exposes his crimes, including his role in the bombings. Cass retreats to Albion's headquarters in the Tower of London, which DedSec storms, and he is killed.

The final chapter's missions are DedSec Party, The Face of the Enemy and Hard Reset. Zero Day hacks DedSec and steals its technology; tracing the attack reveals that Sabine was behind the bombings and Zero Day, and that Cass had helped her before betraying her. She had restarted DedSec to get revenge on Cass and planned to use a patch for Bagley to seize control of ctOS. Bagley agrees to be shut down: one operative lowers the fins on Blume's radio tower, sending Sabine falling to her apparent death, while another shuts down Bagley's main server at Broca Tech (Wikipedia). Afterwards the government reviews Albion's contract, the Metropolitan Police resumes operations and DedSec's names are cleared.