Frank is blindsided when the mayor asks Jamie to be on his security detail on Blue Bloods. "Hidden Motive" is the 17th episode of the show's 12th season.
Baez and Danny investigate grand larceny connected to feuding crime families when one mob family steals the other's wedding gifts on Blue Bloods Season 13 Episode 18.
Frank's dilemma, Erin's investigation, and Danny and Jamie teaming up should make for another lively family dinner on Blue Bloods Season 13 Episode 17.