Reilly's Rangers (quest)

Reilly's Rangers is a side quest in Fallout 3 as well as an achievement/trophy.

Quick walkthrough

 * 1) Talk to Reilly in Underworld or pick up the Ranger emergency frequency.
 * 2) Get to the Statesman Hotel by way of Our Lady of Hope Hospital.
 * 3) Get to the rooftop.
 * 4) Repair the elevator.
 * 5) Get the Rangers back to their compound safely.

Detailed walkthrough
Find Reilly in Underworld, the ghoul city situated in the Museum of History in D.C. (near the Washington Monument). She is lying unconscious in the Underworld hospital, The Chop Shop. You must either convince Doctor Barrows to wake her with a Speech check, or do so yourself, with a Medicine check of 60. Reilly explains that she was wounded by super mutants while trying to ex-filtrate and get help for her team, who are stranded on the roof of the Statesman Hotel. She will ask that you find her team and bring them back to safely. She also tacks on that if you can, find Theo, the mercenary group's quartermaster. Alternatively, the Ranger emergency frequency, an automated distress call from the Rangers stranded on the roof of the Statesman Hotel will be picked up. The signal can be picked up while exploring near the National Archives building at the Mall Northeast map marker, but also on Pennsylvania Avenue and Vernon Square near the Statesman Hotel. The frequency calls for help and instructs rescuers to the top of the Statesman Hotel.

Find the Rangers
Locate the Our Lady of Hope Hospital in Vernon Square. On the second floor of the hospital is a door leading outside to where a radio tower has fallen into the building. This creates a makeshift bridge to the Statesman Hotel, which is otherwise inaccessible.

In the first stairwell you will find the body of the Rangers' quartermaster, Theo, and a locked ammunition box which can only be opened with a code received from Reilly. At an intermediate floor, you must go up to the restaurant level. If your repair skill is high enough, you can fix the elevator at the center of the map by interacting with its control panel. If not, you can also use the stairs through the doorway at the building's northeast corner. On the restaurant level, you'll need to pick an average lock or (to avoid it) you can detour around the lounge, down a collapsed floor into a lower level, up another collapsed floor, through the kitchen, and into the lounge proper (the room with the bar, pool table, and jukebox). In the southwest corner of the lounge there is a small room with a downed maintenance protectron. In the lounge (the big room) go up at right to the balcony where you'll find the door to the roof.

Repair the elevator
As you arrive on the roof, a final round of explosions will take out the latest wave of super mutants. Butcher will then wave you in, but admits you're stuck there with them unless the elevator can be repaired by Donovan. You may speak to each team member and, if you wish, offer them ammunition (Brick takes 150 5mm rounds, Butcher takes 50 10mm rounds, Donovan takes 50 5.56 rounds). Ask Donovan about the elevator and he will tell you that he needs a fission battery and will mention the broken protectron in the restaurant below if you don't have one with you. He can repair the elevator with it, or you can use Repair check of 75 to fix the elevator yourself by accessing its control panel with the fission battery in your inventory. (This will not "use up" the battery.)

Rescue the Rangers
After the elevator has been fixed, the mercenaries will descend. Following this, a battle between mercs and super mutants takes place throughout the hotel. The group escapes through the hotel lobby and hightails it to the Ranger compound in Seward Square. Reilly will have returned to the Ranger headquarters and thank you for your help. She will hand you a geomapper module and ask you to map out locations for them in your travels.

Bugs

 * The Rangers become hostile if any of them are hurt while on the rooftop, regardless of whether or not the player had anything to do with it.
 * The same broken protectron can be found stuck in the floor after initially going to the rooftop and looking for the fission battery after speaking to the Rangers. The protectron will fall halfway through the floor and will make the noise of metal falling onto the floor repeatedly. If this happens just run towards the noise and then just proceed normally once obtaining it.
 * Reilly's Rangers may randomly become hostile to the PC upon return to their HQ. If this happens just reload the save until they are not hostile.This may be because the super mutants are not dead when you get to the Rangers.
 * Reilly's Rangers may become hostile towards the PC if you shoot one of the Ranger's corpses should any of them die after the elevator is repaired.