The Doctor has gathered several characters together to share unusual experiences they've recently had. Character one saw a mysterious figure watching them from a train platform that disappeared. Character two saw a similar figure on a bus that wasn't visible in a selfie but vanished when they turned around. Character three spotted a black silhouette at their window that disappeared when they closed the curtains. The figures left something behind with each person. When the characters realize one is behind them again, the black figure reveals it has been waiting for them.