(SPOILER ALERT: Those not wishing to have key plot points revealed should stop reading.)
Fifteen years ago, Mary Alice – then known as Angela – and husband Paul (Mark Moses) were childless and approached by a junkie, Deirdre, offering to sell them her infant son, Dana. Three years later, after the Youngs had a new life and Dana was renamed Zach, Deirdre returns and demands the child, attacking Paul – and being stabbed to death by Mary Alice (rather than Paul, who had always seemed the suspicious one).
Mary Alice then talks Paul into stuffing Deirdre into Zach's toy chest and burying her under the about-to-be-poured backyard swimming pool.
Not that Paul is without blood on his hands. Earlier in the season, he knocked off a neighbor, Mrs. Huber, who planned to blackmail the couple.
And, possibly to explain the later odd behavior of Zach (now played by Cody Kasch), the toddler witnesses the dead Deirdre in the Youngs' living room.
But wait, there's more. In new developments, teen Zach brutally attacks the sister of Mrs. Huber, who was hatching her own blackmail plot. Zach then goes with a gun to kill the plumber – and boyfriend of Susan (Teri Hatcher) – Mike Delfino (James Denton), who, meanwhile, has kidnapped and plans to off Paul for his part in former girlfriend Deirdre's disappearance.
Meanwhile, Bree (Marcia Cross) loses husband Rex Van De Kamp (Steven Culp) – as in, he dies – because he's been poisoned. Rex exits thinking Bree did it to him, when, in fact, the culprit was her spurned lover, the pharmacist (Roger Bart).
As for cliffhangers: Just as the testimony by Gabrielle Solis (Eva Longoria) is about to get Carlos (Ricardo Chavira) off the hook for an alleged hate crime of beating up gay gardener, John, the hunky yard boy, confesses to his affair with Gabrielle. Carlos explodes in the courtroom.
Stay-at-home mom Lynette Scavo (Felicity Huffman) has been ordered back to work by hubby Tom (Doug Savant) after she sabotaged his promotion at work.
And as real estate agent Edie (Nicollette Sheridan) herself wonders, why has Betty Applewhite (new cast member Alfre Woodard) moved to Wisteria Lane?
All that, and will Zach kill Mike? To be continued. Next season.