Most TV shows are taking the day off on this first day of 2018, showing reruns, but Fox’s interesting Marvel series about young mutants is returning for midseason with a fresh episode, number 11 of its first season. And tonight, with members of the mutant squad wary of one another, tensions run high – and the powers they can wield, including those of Polaris, are much more likely to be at hand. In her case, literally.