Last week, this new series from Stephen King and David E. Kelley began with a horrifying opening sequence: At a snaking line for admittance to a jobs fair, hopeful people gathering hours early for their turns at finding potential employment were mowed down by a murderous motorist. It was chilling to see a week ago, and even more chilling to recall, in retrospect, after this weekend’s horrifying act of vehicular homicide in Charlottesville. And tonight comes episode two, where there’s less violence, but – thanks to a cat-and-mouse game begun by that same killer, aimed at the police investigator who failed to catch him for that earlier crime – no less tension. Mr. Mercedes is a scary, spooky series, but a very good one, with fully committed lead performances by Harry Treadaway and Brendan Gleeson as, respectively, the killer and the retired cop.