Story related and can't be missed.
This achievement is unlocked when you have completed all 8 missions.
*** Spoiler - click to reveal *** Mission 1 - Someone's Knocking: Trace the hacker.
Mission 2 - In Plain Sight: Take out the fixer.
Mission 3 - The Rat's Lair: Lead T-Bone to safety.
Mission 4 - The Defalt Condition: Find and take out JB "Defalt" Marcowics.
Mission 5 - Little Sister: Lead Nicky to safety.
Mission 6 - Ghosts of the Past: Drive Nicky and Jackson out of town.
Mission 7/8 - No Turning Back: Chase and kill Dermot "Lucky" Quinn, and race to save Clara.