The team tracks a serial killer when remains of numerous victims are found in the walls of an elderly couple's home; the hunt becomes urgent after the BAU learns the killer's specific ritual of when to strike; Rossi reconnects with his ex-wife.
The BAU travels to Chicago to investigate a case where red roses are left on victims; Rossi gets an unexpected visit from his ex-wife.
Rossi prepares to marry Krystall; the team investigates a series of fatal shootings following car accidents.