Promised Land by Robert B Parker

The excerpts center on a private investigator named Spenser hired to find a client's runaway wife, Pam Shepard, in Cape Cod. The narrative details Spenser's investigation and observations about modern relationships, including his own evolving dynamic with his girlfriend, Susan Silverman, as he interviews those connected to Pam, like her lover and a local police detective. A major plot turn occurs when Spenser discovers Pam has gotten involved with two radical feminists, Rose and Jane, who committed armed robbery and murder to fund their cause, entangling Spenser in a dangerous criminal plot with a loan shark, King Powers, to whom Pam's husband, Harvey, owes money. Spenser orchestrates an entrapment scheme to capture the criminals and negotiates the release of both Shepards from their respective troubles, ultimately reconciling the couple and culminating in Spenser’s own marriage proposal to Susan.