Doctor Who Season 15's Surprise Sequel Episode Explained: How "The Well" Is Connected To David Tennant's Era

Warning: Spoilers ahead for Doctor Who season 15, episode 3, "The Well."Doctor Who season 15, episode 3, "The Well," begins as though it's going to be a brand-new adventure for the Doctor, but the installment gradually reveals itself as a sequel to a story from David Tennant's era as the Tenth Doctor. The episode that's being continued after almost two decades is Doctor Who season 4, episode 10, "Midnight." The 2008 effort left Ten without his companion during his trip out to see the planet's surface. Although he had people with him, calling them companions would have been a stretch.