Arkham Mansion--Part 4

Track Dr. Young's Fingerprints

Grapple back into the vent and follow it back to the previous room. Battle the three thugs waiting for you, then proceed into the room they emerged from, grab the Interview Tape from the table, then continue through the door and down the stairs. Continue to use detective mode as you follow the fingerprints down the stairs on the left and through the door, into the Main Hall.

Inside the main hall, head right down the stairs then through the door on the left, into the South Corridor. Continue through the hall, take down a couple of guys, then grapple up to the pipes on the left and blow your way through the weak wall for a Chronicle scan, before returning to the ground-floor and proceeding through the far door, leading to the Library.

Take down the enemies inside the library, then grapple up to the top-floor balcony directly above and look for a vent you can enter.