As viewers saw when Grant Gustin was introduced as Barry Allen on Arrow, his mother was murdered by someone with superpowers and his father imprisoned for the crime, leading the future Flash to pursue a career as a crime scene investigator. Harrison’s role is described as “guest starring/recurring,” which presumably means we’ll see Nora in a series of flashbacks, a key storytelling device on Arrow.
Harrison joins a cast that also includes Candice Patton as Iris Allen, Jesse L. Martin as Detective West, Rick Cosnett as Detective Eddie Thawne and Danielle Panabaker as bioengineering expert Caitlin Snow. Those last two are most likely villains Professor Zoom and Killer Frost.
DC Entertainment Chief Creative Officer Geoff Johns and Arrow executive producers Greg Berlanti and Andrew Kreisberg wrote the pilot, which will be directed by David Nutter.