Ruby Sunday (Millie Gibson) loses the Doctor (Ncuti Gatwa) in a fairy circle on a clifftop in rural Wales. She is stuck with a stalker — one who stays exactly 73 yards (aka 219 feet) away, just far enough that Ruby can't quite see or hear her — for the rest of her life.

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That's the premise of "73 Yards," the mind-bending fourth episode of Doctor Who Season 14,...

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