doctor who

A man in a striped shirt and dark jacket stands in a dimly lit cave, his eyes wide and mouth slightly open in a look of shock, as he turns his head to the side; the scene cuts to a grotesque alien creature with a pale, skull-like face and red, textured skin, wearing a dark, ornate robe, who stares forward with a menacing expression; the man reappears, still displaying the same startled expression, before the video abruptly cuts to a street scene of a marathon with runners and spectators, overlaid with text reading "Explosion at Boston Marathon."