See gargoyle and try to talk to zombies in queue.
Go right. See the opened coffin, the tomb and opened grave (get brain).
Try to enter the factory. Talk to Agent Superball - he wont let you in because of queue. See garlic clove cigarettes in trash container.
Go left and throw brain on gargoyle. Zombies will run for it. Now you can enter the factory.
Meet Jurgen. Talk to him twice.
Take the bottle from the bar and go behind DJ Booth. Check all buttons. Each one has a special effect. Buttons on the middle have vocal effects and blue buttons change the music.
Read the rhyme from the coffin:
My dark mistress longs for death
To return to her velvet sepulcher
Her only passion the void's embrace
Or else she'd reply to my letters.
Last words are the key to open secret passage.