Haven't They Grown (UK) AKA Perfect Little Children (USA)

London mother and massage therapist Beth Leeson hasn’t seen her former BFF Flora Braid in more than twelve years, not since their friendship fractured and the Braids moved away. But her son’s soccer game puts Beth in the vicinity of their last known address and she can’t resist the urge to do a quick drive-by to scope out their house. This simple act throws Beth’s life into complete chaos when she witnesses the unfathomable: Flora tending to her two children, Thomas and Emily, who appear exactly as they did more than a decade ago rather than as the teenagers they should have grown up to be.

Despite her husband Dom’s incredulity, Beth is firmly convinced that she saw (and heard) correctly, and vows to get to the bottom of things. Willing to humor her, at least initially, Dom does a search across social media platforms and finds that Flora’s husband, Lewis, is now living in Florida; pictures show him posed there with the appropriately aged Thomas and Emily—but there’s no evidence of Flora or their youngest child, Georgina. Rather than putting her mind at ease, this internet sleuthing—and the questions it raises—further incites Beth’s need to discover the truth of the matter; after all, she can’t help but thinking Flora and the children may be in danger. But digging into the past can be a deadly proposition.