Gyaarah Gyaarah, out on ZEE5 and adapted from the Korean series Signal, is a time-warping thriller of the dour, soulless kind. Tumbling across timelines, director Umesh Bist always makes sure to hold his audience’s hand. Bland letters appear on screen to indicate the precise date, year, location. Lest we lose our bearings, the pop-culture references are even more plain: Dil for 1990, Kapoor & Sons for 2016. This is a fairly unimaginative way to summon a period, to evoke a mood. It’s unlike the scene in Back to the Future where Doc in the 1950s exclaims to Marty, who’s traveled back from the 80s, “Ronald Reagan! The actor?! Then who’s vice president? Jerry Lewis?”