Pick this one up by driving around Haarfel. You'll see a blue exclamation spontaneously populate in this location (near one of the Cultivation samples).
Investigate the marked building to find a number of non-human exiles in a severely altered state. Only the salarian has a shred of rationality- he'll draw your attention to a datapad before signing off with a Prisoner reference.
Read the datapad on the floor, and follow the navpoint just to the other side of the valley, and talk to to the scientists within (you may need to exterminate any nearby wildlife in order to enter conversation).
These are ex Cerberus types, and true to form, they're performing terrible experiments on unwilling victims. There are no really happy endings here- there's no way to heal the afflicted, and you can't properly bring the scientists to justice. Make whatever choice your Ryder is most comfortable with for a reasonable Viability reward (unless you choose to leave them be. But you didn't, did you?)
You can also follow up with the mind-gamed exiles later, but there's nothing you can do to help. Even if you choose to happify them, there seems to be no guarantee they'll be to feed themselves, or anything.