This two-hander starring Mary-Louise Parker and Denis Arndt features Parker as a quirky fortysomething who turns a seventysomething Irish butcher’s life upside down when she gives him a spontaneous kiss on the neck in a London train station. This surprising love story—named after the physicist responsible for the uncertainty principle—is by Simon Stephens, who won a Tony for adapting The Curious Incident of the Dog in the Night-Time for the stage. Parker has made a career out of portraying normal-seeming characters who are in fact teetering on the edge. When Heisenberg premiered at MTC’s Off-Broadway space in 2015 she was heralded for bringing that same combination of courage and fragility to her character, Georgie. Arndt has also received ample praise for his performance.