Spread over 30 years, these books comprise Asimov’s robot detective stories starring Lije Baley and R. Daneel Olivaw. (The R. stands for Robot) All are murder mysteries of a sort that are premised upon a paradox that is caused by the three “Laws of Robotics” that regulate the behavior of robots. In each, Baley solves the dilemma and smoothes over inter-galactic tactility but manages to allow the culprit to escape castigation.