In the first episode of Ex Nihilo Theater’s six-part series, Terra Incognita, performed at the Octopus Literary Salon (2101 Webster St., Oakland), three estranged sisters alternate between squabbling and reminiscing outside of a gas station in Reno, Nevada. The air is hot, and tempers are, too. It’s the beginning of a journey that will take the trio across the country, as they cart their mother’s ashes to fulfill her dying wish: to go over the Niagara Falls in a barrel urn. The morbid premise offers plenty of fodder for dark, witty humor, just as the siblings’ banter provides a handy platform to drive the narrative while also offering insights into the sisters’ individual and collective histories. The idea of roadtripping is also the perfect metaphor for Ex Nihilo Theater’s serial endeavor, set to unfold every two months over the next year. The company, which Bridgette Dutta Portman, Elizabeth Flanagan, and Jennifer Lynne Roberts co-founded in 2014, is an experiment in breaking boundaries, taking risks, and overcoming roadblocks. The playwrights are recording each episode, available on ExNihiloTheater.Weebly.com, so, in case you missed the first part, there is an opportunity to catch up before the second episode, set in Bottle Hollow, Utah, on December 17.