Complex sentence: Blackie wants to stop Mary singing at the Tivoli, and although he arrives the night of her premiere with a process server to shut down the show, when he hears her sing he decides not to stop the opera.
Split into simpler sentences: Blackie wants to stop Mary singing at the Tivoli: he arrives the night of her premiere with a process server in tow to shut down the show. However, when he hears her sing he decides not to stop the opera.