The Oscar- and Emmy-winning actress will play a genetic genealogist in Blood Relative. Based on a 2018 Cleveland Scene article, Blood Relative revolves around Leo's Louise Kelly, "who knows the field of genetic genealogy better than anyone but is also impossible to work with," per The Hollywood Reporter. "With an IQ in the 190s, Lou wrote the book on genetic genealogy and can trace anyone if she has a viable tissue sample to play with — John and Jane Does, errant husbands, long-lost children, murderers in hiding, anyone with a secret life." The casting marks a return to Fox for Leo, who's starring in HBO's upcoming miniseries I Know This Much Is True. Leo starred in Fox's Wayward Pines in its first season in 2015.