A glitch with the passage. (Assassin's Creed: Syndicate)

Help to deal with the problem. Stopped at the mission of Marx, where you need some kind of anarchist to catch with nitroglycerin. When Marx, I listened, immediately went to him, and then I wrote the anarchist was killed, load save, again, the anarchist was killed and again the save game to be loaded...How can this vicious circle be removed?