On this page of our Marvel's Spider-Man solution you will find a description of Back to School mission. Peter goes to a costume ball to find a scientist...
The scientist you search for, Delaney, is dressed up as "one of the greatest enemies" of Spider Man. Go straight ahead and pass the dressed-up people. Finally, you'll reach out to someone dressed up as a Mysterio - approach and follow this person. At the end of the tunnel, you'll expose her mask and find out that it's not your target.
Go outside - another suspicious person is a man dressed up as Vulture. Use R2 to jump onto the balcony where the suspect resides and talk to him. Go down and run towards the location of located doctor.
On the court you will be attacked by an individual dressed as Rhino. Free yourself from the grasp and run behind the kidnapped doctor. Run onto the building and enter through the window. Help detained teenagers and defeat the Demon Gang group. Then, enter the ventilation shaft and go to the next room with opponents.
After the fight, go out of the window and go through the wall to the next shaft. An interesting cutscene awaits you, after which you will face your enemies. Use gadgets - especially to neutralize brutes and enemies with a whip.
After the fight, get outside. Martin Li will use his power to turn the disguised into zombies to attack you. The enemies are quite weak - the only worthy opponent may be a guy wearing Rhino's costume. After the battle, the police arrives and you will successfully complete the mission with 3000 XP.