Disney+ K-drama Grid: slick sci-fi procedural starring Seo Kang-joon and Kim Ah-joong is seemingly all mystery and no depth

• At its best Grid is reminiscent of glossy American sci-fi-fantasy-action shows such as Heroes, and boasts a strong cast and slick production values
• But so far, the series has stubbornly refused to sketch out its characters fully and clearly explain the world in which they exist