Complex sentence: Jackie leads her ex-boyfriend Nick to the vampire's flat so they can drink his blood: he escapes before they can kill him, but as he leaves the flat, Petyr attacks him and later turns Nick into a vampire.
Split into simpler sentences: Jackie leads her ex-boyfriend Nick to the vampire's flat so they can drink his blood, but he escapes before they kill him. As he leaves the flat, Petyr attacks him and later turns Nick into a vampire.