Critic Consensus: A bit of narrative weakness aside, "Knock Knock" is a wonderful mix of nostalgia, horror, humor, and monsters that culminates into a powerful and emotionally complex episode.
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Critic reviews for Knock Knock
From creaking floorboards to claps of thunder, whistling wind to slamming doors, this knowingly nostalgic episode was styled like an old Hammer horror flick.
I think it's about time to call it: This season of Doctor Who is shaping up to be a real yawn.
"Knock Knock" is the first time in a very long while something on Who managed to actually scare me in more than just a particularly chilling concept.
As much as the hour hinges on Suchet's turn from malevolent landlord to weepy mama's boy, "Knock Knock" is also interested in being an early turning point of the season.
"Knock Knock" is a nice mix of horror, humor, and monsters of the week (space fleas!) amid an ultimately tragic tale about what happens if you can't get on with your life and let nature take its course.
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