I'm trying to do the mission I Put a Spell on You. I staked out the control tower until I saw the mole go inside. Then I ran in and pulled out my shotgun. The mole said "You're getting too close, Seamus!" and pulled out his gun, so I killed him.
The game then tells me to go back to Hsu. When I talk to him about what happens, he tells me to go check on the monorail because he thinks it's been sabotaged. I make a beeline for the monorail, but as soon as I walk through the door to the platform, I hear "The train is departing, please keep bla bla bla" and it immediately rockets off towards the Strip before I can get to it, promptly exploding a couple of hundred yards down the track.
Did I screw up by not listening to the mole talking on the radio, or something? Is the quest not completeable anymore? If so, are there any console commands I can use to fix this?