A couple found dead in a quiet Bucks County home leave Detective Christopher Petrowski with few leads to follow; he questions a young girl whom he finds oddly familiar.

Petrowski gets a lead on his double homicide case when a family member of the deceased comes snooping around the crime scene; Petrowski attempts to reconcile with his daughter, Rebecca, and realises why he recognised the young girl on the stoop.

An unexpected high-priced attorney comes to rescue the meth-dealing Will Pepper, forcing Petrowski's captain to let him walk; Petrowski visits the site of a former cold case and bumps into the girl from the Walsh crime scene.

During a stakeout, Petrowski's new friend reveals her identity, causing him to have a near breakdown; Malik's brother Aamir scolds him for tagging a bridge; Petrowski has something to show Angela that she might not be ready to see.

While Mr. Peck continues to fly under the radar as Bucks County's biggest meth dealer, Petrowski and Angela retrace the last moments leading up to her death; Rebecca invites her Father to Chloe's fifth birthday party and Angela reveals a strong lead.

After being arrested under suspicion of multiple homicides, Mr. Peck comes up clean; Petrowski shows up late for Chloe's fifth birthday, causing more discord in his relationship with Rebecca; Aamir clues Petrowski into a new lead.