Guess Who I Saw Today

Guess Who I Saw Today is a side quest in Fallout: New Vegas.

Detailed walkthrough
To begin the quest you must go to the Jacobstown Lodge and talk to Doctor Henry and tell him you will help him with looking into why the local night stalkers have begun turning invisible.

Meet with Lily, a smaller nightkin standing by the pen outside the front of the lodge after accepting the quest. You can invite her to come with you, but do not have to (this will only work if you do not have a fellow humanoid companion already).

Exit Jacobstown and circle around to the northwest to locate Charleston Cave, and enter. Continue through the cave following your compass (generally moving downhill) while dispatching night stalkers and eventually you'll come across a couple of bighorner bodies and a nightkin body, with Oh, Baby! next to it. Examine the nightkin and take his chewed Stealth Boy and you'll be prompted to return to Doctor Henry back in the Jacobstown lodge.

(The night stalkers will not attack if the player has the 'Animal Friend' perk.)

Back at Jacobstown, talk to the doctor. He'll inform you that since the chewed Stealth Boy was a dead-end, using the Mark II Stealth Boy is the only remaining line of research available to him, and Lily is his best experimental subject. Talk to both the doctor and Lily (Note: If you talk to Lily while you are away from Jacobstown, she will run back to Jacobstown. So if you need her, be careful where you have this conversation.), they both will agree to the experiment. It's a success, but as soon as the doctor is finished Keene enters the room and demands the Stealth Boy Mk. II specs.

Make sure Doctor Henry actually does the experiment, you should not have to wait more than 30 seconds for him to start
 * If you can pass a Speech check (80), Keene can be spoken down.
 * Giving him the specs will cause him to leave peacefully.
 * If you don't give him the specs, he and two other nightkin will attack.
 * You can easily draw the three of them outside and let the super mutants help you do your work.
 * You can also go in the corner (where the wheeled tables are) to prevent the nightkin from attacking you (or delaying them).
 * It is possible to use a Stealth Boy and reverse pickpocket C4 plastic explosive onto Keene and his 2 nightkin before speaking with him. This way, if you chose to fight them, you can use a detonator to instantly kill all 3 at once.
 * Note, Lily will leave the lodge as Keene is coming into the room, she will therefore not help you with the fight**
 * Lily will start firing at you as well**

In the lodge, speak with Doctor Henry again.
 * If you can pass a Science check (90) you can convince Henry to test the Stealth Boys on night stalker brains.
 * You can also inform the Doctor the risk is too great, and Lily should not wear it.
 * You can also tell him you think Lily should continue to wear the Mark II prototype.

Whichever decision you choose, it will end the quest. It is not confirmed if different decisions have any effect on game-play, though you will always be able to take Lily as a companion. Passing the Science check gives you around 100 more experience than the other two options do. Passing with the science check awards 590 XP.

No matter the outcome, the player will NOT be able to acquire the Stealth Boy MK II Prototype.

Bugs

 * If you manage to get to Doctor Henry before Lily arrives, you can still initiate the test. This will cause Henry to talk to the absent Lily and break the sequence, having Henry standing there unresponsive, waiting for Lily to act.
 * If Calamity is not present there will be a long pause in the dialogue when Doctor Henry asks for the results and Calamity's words will not be spoken.
 * Apart from reloading, there are several methods to make Doctor Henry responsive again, so that at least the quest "For Auld Lang Syne" can be finished:
 * Failing a pickpocket attempt on Henry may reset his AI after he confiscated your stolen goods.
 * Although, pickpocketing him sometimes makes Jacobstown residents hostile towards you.
 * Waiting for 24 hours may trigger the next stage of the sequence.
 * Calamity may be stuck in her room (right-hand passage behind the reception counter, second room on the left). Engaging with her (even just buying something) allows her to start to move out to join Doctor Henry, allowing the 'tests' to complete.
 * Immediately after using the speech option with Keene telling Doctor Henry to do as he says, there will be a black screen crash. this happened on the PS3 and the Xbox 360.
 * Sometimes, if you beat Lily to the lodge trying to exit the building again will cause a black screen crash. There is no fix for this at this time aside from exiting the game, erasing all add-on content (including patches) and loading the game with out the add-ons.
 * If you come back to the lodge whilst the quest "Eureka!" is active, Doctor Henry may not respond to you talking to him, resulting in it being impossible to finish the quest.
 * If you go into V.A.T.S. on Lily while she is testing the Stealth Boy MK II and she is invisible she will turn visible but this will not affect the quest.
 * If you ask Lily to help Doctor Henry while she is waiting in the Presidential Suite of the Lucky 38 without asking her to come with you, she will immediately leave to go speak to Doctor Henry. When you return to Jacobstown Lily will not be present anywhere, but you can stil talk to Doctor Henry to initiate the quest. He will go through the dialogue one sentence at a time, and the only solution to get the quest finished is to leave the building and return to Doctor Henry after each line. (This solution does not seem to work on 360.)

Behind the scenes
"Guess Who I Saw Today" was a soft jazz song written by Murray Grand and performed by Elisse Boyd.

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