I Put a Spell on You

I Put a Spell on You is a side quest in Fallout: New Vegas.

Synopsis
Colonel James Hsu is concerned that there is a spy somewhere around Camp McCarran leaking vital information to Caesar's Legion, and asks for an outsider's help in finding the culprit.

New California Republic

 * 1) Talk to Captain Curtis or Colonel Hsu about problems around Camp McCarran.
 * 2) Talk to Lieutenant Boyd about the break-ins.
 * 3) Check out the control tower during the night (between 1:00 and 2:00 AM) and listen in on the spy.
 * 4) Defuse the bomb on the NCR monorail with an Explosives check of 35, a Science check of 45, or with the activation code that can be pickpocketed from Captain Curtis.
 * 5) Report back to Colonel Hsu.

Caesar's Legion

 * 1) Talk to Captain Curtis or Colonel Hsu about problems around Camp McCarran.
 * 2) Talk to Lieutenant Boyd about the break-ins.
 * 3) Check out the control tower during the night and confront Curtis. With an Intelligence of 8, or having completed The Finger of Suspicion, the Courier can help Curtis in his sabotage.
 * 4) Pick up the items in the garbage bin.
 * 5) Plant the bomb on the monorail.
 * 6) Put the items (Abraxo cleaner, conductor, fission battery, wonderglue and monorail sabotage plans) into Davey Crenshaw's footlocker in the concourse's upper story.
 * 7) Report to Colonel Hsu and tell him about the evidence in the footlocker.
 * 8) Report to Captain Curtis and tell him he's in the clear.

Behind the scenes
The title of the quest is a cultural reference to the song "I Put a Spell on You", written by Screamin' Jay Hawkins in 1956.

Bugs

 * If you help the Legion blow up the monorail but do not have a high enough Speech or reputation level with the NCR for them to help you, you have to go back to Curtis and say "Hsu won't let me help". Curtis then tells you to rig the monorail to explode regardless. However, a glitch may mean that you can't plant the bomb, making the quest impossible to complete. The monorail can still be used to travel to The Strip.
 * If you're on bad terms with the NCR and initiate this quest as a Legion supporter, then get on good terms and speak to the Colonel about completing the quest for the NCR, the explosives in the trash can become non-existent and the Control Tower becomes vacant.
 * You may not be able to enter the monorail because of a invisible wall glitch before you inform Hsu.
 * There is a chance that the explosives will not be in the trash can by the ticket counter.
 * Sometimes no matter what time or day you're there, the spy will never show up. A possible solution is to reload an earlier save.
 * Upon entering the tower, followers get stuck in an endless loop of appearing a few feet above the ground, settling on the ground, and then reappearing back in the air again.
 * After successfully entering and eavesdropping on the spy, leaving the control tower causes any followers to stop following. They will wait in front of the tower until you talk to them and tell them to stop following and then to follow you again.
 * If you end this quest without saving the monorail, Hsu will not grant you the reinforcements for Bitter Springs, thus making the Quest No, Not Much unsolvable. However, reaching Liked status with the NCR allows Hsu to send the reinforcements before completing this quest.
 * If you started the quest from Hsu, you can still "start" Inculta's side of the quest, effectively exposing the plan to blow up the monorail long before you would normally find out (if you are following the NCR's side of the quest). By the end of the quest, attempting to disarm the bomb will instead force you to plant it, regardless of a bomb already clearly being there. The vent then can be clicked again, ultimately disarming the bomb. Leaving the train will cause it to speed off and explode but you can return to Hsu and tell him of Curtis' "attempted" plot, regardless of the fact that the monorail just exploded.
 * The monorail will not permit entry in order to diffuse/plant the bomb and instead only show 'Take monorail to the Strip'.
 * After you start the quest make sure to get the key to the control room from Boyd before starting the interrogation; interrogating Silus and killing him will make Boyd impossible to talk or pick-pocketable, making this quest impossible because she gives you the key to the control room.
 * If you are helping the Legion, sometimes after you plant the bomb on the monorail, the monorail will not leave the station rendering the quest useless.
 * When you disarm the bomb on the monorail, you will not have the dialogue option with Colonel Hsu to finish the quest.