Resident Evil 2 - Leon A - Part 2: Ada Wong
Fall through the upper floor of the Library and activate the switch (4:40). Push the first and second bookshelves to the right to get the Bishop Plug. Use the Square Crank on the third floor to activate a staircase (9:41). Use a Small Key on the drawer in the hallway near the Library to get the Handgun Parts (13:10).
Grab the Valve Handle (17:00) and use it to put out the fire around the chopper (18:22). Use the two Virgin Hearts in the room that was blocked by fire to get the King Plug and grab the Diamond Key (21:03). Use the key to get to the evidence room. In the next room, grab the Heart Key (28:28).
Use the Heart Key to enter the Interrogation Room and grab the Cord and Rook Plug (32:25). You can use the Cord in one of two places, the best of which is the hallway leading to the basement (34:26).
In the power room, flip the switches in this order: up, down, up, down & up (40:10).
Leon encounters Ada Wong, who is looking for her boyfriend John (41:30). They question the reporter Ben for information (46:45). After talking with Ben, grab the Manhole Opener (49:22). Use it in the Kennel to reach the sewers.