Deadly Honeymoon by Don Potter

Newlyweds face murder and conspiracy in an island paradise. Katie and Mac move to New York City after fighting the forces behind a subliminal advertising scheme in the nation's capital. Six months later, while on their honeymoon in Puerto Rico, they are drawn into the investigation of a murder at their hotel by a hard-drinking local newspaper reporter. As more deaths occur, the suspect list grows to conspiracy proportions. Katie's father, Ben Norris, has business interests on the island and volunteers his services even though the newlyweds are committed to solving the case on their own. If solid evidence of a conspiracy is not uncovered, Puerto Rico could suffer grave financial consequences. The situation becomes more dangerous as the sleuthing couple races to expose the explosive plot before time runs out.