context: After witnessing an uncontrollable blaze burn her family's pizzeria to the ground when she was just 11 years old. It's
  no wonder that Reena (Alicia Witt) decides to become an arson investigator. Now, years later, our all-grown-up heroine decides to visit the old neighborhood, where she finds true romance with a hunky carpenter named Bo
  Goodnight (Matthew Settle). But Reena is swiftly knocked off cloud nine when she discovers that a psycho connected
  to her past has resurfaced to wreak havoc in her life. It turns out this villain has an unhealthy obsession with torching
  things (or people!) who are near and dear to Reena. Now she must use her sleuthing skills to snare this pyromaniac
  before her life (and love) go up in flames - literally!
question: Who shows up from Reena's past as her relationship with Bo starts?
answer: A psycho