A hunt for fireflies turns gruesome when an 8-year-old's slumber party turns into a crime scene. Sparks fly when Callie joins the F.D.L.E. as a forensic nurse. When a Navy recruiter is murdered, his sexy ex-wife unravels under Jim's intense interrogation. It turns out that her new, younger boyfriend was caring for her infant son, but now the baby is missing. Jim and Callie must race against the clock to find the killer and the baby alive. Natalia Cigliuti guest stars.