My Bloody Valentine (mission)

See this mission and the prerequisite mission, Youth Outreach, on Wikia

Youth Outreach is the prerequisite for this mission.

Dead Stories side mission can be obtained during this mission, in the Fear Nothing clubhouse.

The mutually exclusive "Doing it Right" and "Doing it Wrong" achievements can be obtained by running this mission two times. Doing both opens up the "Losing Your Religion" achievement.

Reading the notes will not only tell the story of the Fear Nothing clubhouse and its Morninglight masters, but give clues to the location of keycards and suchlike required items.

Find a Chip and a Coat and assemble them to place the Chipped Coat on the Hangar to open the secret door.

Run back before the Filth attack; destroy the pillars to cross the Filth and get back to the boss battle.

The mission completes when "the room where the assassin lurked" is entered, but there may be side missions still to complete and even one to find; One Kill Ahead can be received from the computer terminal

The final journal page may well be in the cathedral boss battle area, either because it is a big area and a small page is easily missed, or because it does not spawn until after a particular mission step.

Links
https://www.reddit.com/r/SecretWorldLegends/comments/72535s/kaidan_side_missions_route_map/