Perhaps their strikingly different personalities make the relationship between detective Jane Rizzoli and medical examiner Maura Isles so effective. Jane, the only female cop in Boston's homicide division, is tough, relentless and rarely lets her guard down, while the impeccably dressed Maura displays a sometimes icy temperament — she is, after all, more comfortable among the dead than the living. Together, the best friends have forged a quirky and supportive relationship; they drop the protective shield in each other's company, and combine their expertise to solve Boston's most complex cases.

The fates of an aging hitman and a washed up detective become entwined when one last job leads to one last chance to settle an old score.