"The Caves Of Steel" was Asimov's first SF/crime/mystery crossover novel and shows Earth suppressed by the long-lived superior "Spacers". When the spacer ambassador to Earth is killed an investigation by a mismatched pair of investigators, one from Earth and the other a Spacer must find the killer and avoid an interstellar incident. Well crafted characters and thoroughly plotted this is an excellent book for fans of either genre.