Doctor Who’s unexpected best episode yet exposes the show’s biggest problem

This has been one of the best Doctor Who episodes of the season, but feels too little, too late for Ruby Sunday (Picture: BBC Studios/Bad Wolf/Lara Cornell)Spoilers ahead for Doctor Who episode four, Lucky Day.The latest episode of the hit BBC sci-fi series returns to present-day Earth, where we check back in with former companion Ruby Sunday (Millie Gibson), who is settling into normal life after discovering her biological mother at the end of the last season.The episode, unexpectedly, is the