Chris Pratt posted a short video to his Instagram today, revealing a mysterious ice cave that leads somewhere quite unexpected, the actor believes. Pratt, a goofy everyman who just happens to be a megastar, is in Iceland filming The Tomorrow War. The sci-fi actioner, formerly titled Ghost Draft, boasts an ensemble cast including Yvonne Strahovski, Mary Lynn Rajskub, Sam Richardson, Betty Gilpin, Edwin Hodge, and the incomparable J.K. Simmons, who appears in the video sporting a beard as white as an Icelandic winter. Directed by The Lego Batman films’ Chris McKay, little is known about the plot of …