Tread Perilously concludes the Summer Grab Bag with the third episode of Cop Rock -- "Happy Mudder's Day."

Hollander continues his pursuit of LaRusso -- now centering in on Potts and offering him immunity if he testifies against his partner. The mayor receives some difficult news from her image consultants and goes under the knife to initiate a bid for the Senate. Rose hits a breaking point with Gaines as a domestic call turns into one of the stranger musical numbers either has witnessed. Vicki, Ruskin, and Campo take a back seat as guest characters and the chief of police take point in this week's songs. Is it a sign of things to come?

Erik and Justin try to figure out the mystery of Paul McCrane's sudden presence on the show. The mayor's storyline comes under scrutiny as actor Barbara Bosson was married to creator Steven Bochco at the time. Justin comes to believe The Shield creator Shawn Ryan watched Cop Rock. Comparisons abound. Guest characters leading the songs seems to prove the premise was already running out of steam. Erik determines Ron Howard's best films. Vondie Curtis-Hall once again proves dependable and the lack of proper area knowledge around the production becomes more and more obvious.