Hi guys, I'm playing through Fallout 4 for the first time and I've gotten up to the Underground Undercover quest. I'm experiencing an issue where I've talked to Liam and he asked me to find a password for him. The mission log tells me to go and talk to Desdemona, however soon as I leave the institute I immediately fail the mission and it starts the Burning Cover quest. I've talked to everyone in the Institute as far as I know and interacted with everything I can see.

I've googled the problem, however it seems nobody else seems to have this specific problem. All the walk throughs I've read say once you've talked to Liam go back to Railroad HQ and talk to Desdemona, which in my case instantly fails the mission. Is there something I'm doing wrong ?

Any help would be appreciated,

Cheers.

According to the Wiki, you need to complete Institutionalised before you can leave peacefully. If you told Father that you will not join the institute, you will be allowed to leave but can't come back, and hence cannot complete Underground Undercover.