The vibrant work of a street artist catches Jane's eye when she and Maura are called to a back alley where a homeless Marine veteran lies murdered. Bernard Avery survived a tour in Fallujah only to end up hacked to death in Boston. Is his death related to some tragic event during his military service overseas? Is a vital clue staring at them from the alley walls, which are decorated with graffiti? Jane thinks the street art is criminal vandalism, but Maura sees genius in those spray-painted walls – and it won't be the first time they disagree about the meaning of art.
At the veteran's center where Bernard Avery was being treated for PTSD, Jane is shocked to discover the love of her life, Lt. Colonel Casey Jones, is in charge. Since Casey left for duty in Afghanistan, Jane has been pining for his return. Now she learns that Casey's been back in Boston for months, yet he never called her. His coldness toward her makes it clear their love affair is over. Heartbroken, she struggles to focus on the murder investigation, but can't stop obsessing over why Casey left her.
Maura's love life, meanwhile, springs shockingly to life when a hunky corpse in the morgue turns out to be not so dead after all. After Maura revives him, the grateful "corpse" returns to thank her. He's both an artist and a charmer, and sparks instantly fly between them. Their first date is so wild and outrageously fun that Maura impulsively spray-paints a wall...just as the police show up. Mortified, Maura worries that a jail cell may be in her future.
When another homeless veteran is found murdered, Jane and Maura must set aside their personal turmoil and track down a killer who isn't satisfied with only two victims. The vital clues may be locked up in the addled mind of a homeless man – and in a piece of startling evidence that's right under Jane's nose.