Terrific episode for those who don't mind a dash of sci-fi in their Hitchcock. Young entrepreneur Peter Lazar sends away for a mushroom deal that promises quick profits by growing them in your own home. He's excited, and so are his Ozzie and Harriet parents. The next day a neighbor darkly summons Dad with incredible stories about people disappearing for no reason. Dad is unsettled since the neighbor seems so convincing, but then he becomes alarmed when the neighbor too inexplicably drops out of sight. What's going on? The final scene is one of the spookiest of all the Hitchcock entries.
Ray Bradbury did the script, accounting for why the details add up so effectively and the suspense builds so nicely. The lines including the voice-overs are especially literate and unsettling. In fact, this is one of those typically 50's productions that implies a sense of mounting unease beneath an outwardly calm and composed suburbia that might at any moment be invaded by an insidious enemy. Also, notice how in crossing the street early on, Dad has to suddenly stop for a honking car. It's a clever touch like this suggesting unseen danger (likely director Norman Lloyd's touch) that separates outstanding half-hours from merely good ones. Never mind that the idea here bears a distinct resemblance to the classic Invasion of the Body Snatchers. This one is so well done you'll hardly notice.