After your introduction to the Resistance on Voeld, talk to Haana in the garage to start this quest.
She'll tell you about a demolitions expert lost in raid against the kett, but who might have had the skill to survive. She'll give you a nav point southeast of the the base- take the NOMAD and check it out.
Everyone's dead, but if you scan the site, SAM will detect an intact generator underground.
Head uphill, following your marker, and inside the complex.
You can hear the scout, but not reach her through the sealed door. Scanning will reveal the necessary generator in the next room down. Amberish rubble bars the way, but is (eventually) destructable.
Activate the console inside, then head back to the scout for an unsavory discovery.
It turns out she's spent all this time torturing a Kett survivor, in hopes of finding her lost family. You have the choice to execute the Kett and send Mashal back to HQ, or leave her to continue her work here. There's no lasting consequence to either action, though Haana prefers it if you bring Mashal home. Either way, follow up with Haana in the garage to complete the quest.