"Assassinate Pearl Attaway" is a mission objective in Sequence 5 / Memory: End Of The Line
Walkthrough[edit]
Head down to the train tracks where you can see Pearl Attaway in the train car.
Get on the top of the trains and eliminate the Watcher Blighters that are on top of the carriages.
From there just head over to the marker on the train carriage. This will trigger the cutscene for the unique kill of Pearl Attaway