Common Sense - Book #4 of the Common Denominator Series by Richard David Bach

While they're busy chasing down the mad scientist who's kidnapping amnesiacs to mess with their minds and trying to avoid being the next victims in a plot that could devastate Major League Baseball and kill them in the process, newly-wed private investigators Raam Commoner and Kayman Karl just don't have a lot of time for foreplay. But somehow they manage to take some detours through the bedroom on route from a farmhouse in Montana to a major league baseball stadium to a Las Vegas brothel in a near fatal race to wring some common sense out of a lying client and a well-funded conspiracy.