“City of Lies” sometimes gets lost in the weeds of the complex and convoluted entanglements connecting Tupac and Biggie and Suge Knight and some breathtakingly corrupt cops; after all, we know the murders remain unsolved, despite the best efforts of an honest cop and a dogged journalist. Still, in large part due to the stellar work from Depp and Whitaker, this is a valuable and somewhat illuminating look back at the senseless, stunning killings of two rap icons just six months apart. Richard Roeper