Watch Dogs: Legion Clarion Call main mission starts right after you complete the “Light a Spark” mission where you bring down the Albion propaganda. Clarion Call is a rather short mission where you need to hack a drone in the underground subway, gather some data, and blow things up.
Your first objective is to meet with the DedSec informant. Use the yellow marker on the mini-map to reach the informant’s location in Watch Dogs: Legion. The informant is waiting for you at st. Pancras International. Speak with the informant to start a brief cutscene.
Watch Dogs: Legion Clarion Call Walkthrough
After you speak with the informant the mini-map will update with a new yellow marker that takes you across the street. Follow the marker to reach a door and open it to enter a section of the King’s Cross Subway. There is a power generator inside King’s Cross and you objective to blow it up to stop Albion’s operations in the area.
However, you need to hijack a drone first. The door you entered before takes you to an open area in King’s Cross. From the left window use your hacking skills to hijack the gadget outside the window. Turn the camera left to locate another camera you can hijack. Once you reach the second camera, hijack another camera that’s right in front of it on the other side of the platform. There should be a drone under this camera, hijack the drone to take control of it.
Your objective now is to find information on the generator. The information location is marked with a yellow marker. When you reach the schematics, take a picture and then move on to downloading the destination codes on the opposite side of the station. Once you have the codes, use an opening on the wall behind the table and locate the generator by following the yellow marker. Use the detonation codes to blow up the generator and liberate Camden.