As soon as you get there, you hole yourself up in the Tower. While you're developing the negative, your lungs begin to fill with smoke. You can hear Kearnen shooting in the distance, buying you time from whoever's making that smoke. In gratitude, she's the first one you show the photograph to. She nods knowingly. "Mortwake. Those zombies following him would be the Furlbrows." It's now a familiar drive to his tower, out of the smoking ruins of Sentinel Hill, away from the Marshal screaming curses at whoever burned the place down. You didn't have time to get the background, but soon you'll learn. Mortwake is faffing about outside his tower and seems almost pleased to see you. "DO YOU APPRECIATE MY HANDIWORK?" he calls over your engine's loud growl. "Go to hell, Mortwake," Kearnen quietly growls under your engine. You shut off the engine. Now you can hear Mortwake's quieter, but still loud, comments to his zombies. They do look like the Furlbrows. "And here everyone thinks I am a pyromaniac," he says. "Hahahahaha! I just take advantage of the chaos to raise you into undeath. Really, the Defias in Moonbrook burn things! I just raise zombies! Hoohoohoohoohoo!" Kearnen has already assumed a sniper position atop your tank, clearly waiting for you to give the word to gun him down. Moonbrook is clearly your next destination, but first you need to:
Give the word. Get Kearnen back inside. Killing Mortwake won't help you. For that matter, he has the capacity to raise a zombie army. Why not recruit him?