They Shall Not Pass is a side quest in Dragon Age: Inquisition.
Judicael's Crossing has been destroyed, presumably by the Red Templars, to restrict access into the region. Inspect the bridge to see if it can be repaired.
Acquisition
After capturing Suledin Keep (see the quest Capturing Suledin Keep), Baron Edouard Desjardins will be available there. Speak to him and he will give you this quest.
Walkthrough
Go to the bridge and acquire the operation, Restore Judicael's Crossing.
Note
- If you rebuild Judicael's Crossing before speaking with the baron, the quest will not be triggered but the quest icon will still be shown on the map.