Lynette finds out who was responsible for setting the fire at Rick's restaurant; Susan reconnects with ex-husband Karl; Bree gives Orson an ultimatum.

In Part 1 of the two-part fourth-season finale, Kayla accuses Lynette of child abuse; Susan and Mike have a disagreement about their newborn son following the death of Mike's grandfather; the police close in on Ellie; Bree's pastor returns from a mission in Korea; and Katherine's two husbands, Adam and Wayne, meet.