Rees will play a priest who has a connection to Dr. Henry Morgan (Ioan Gruffudd), a medical examiner who struggles to understand why he is immortal. The cast also includes Judd Hirsch, Alana De La Garza, Lorraine Toussaint, Donnie Keshawarz and Joel David Moore. Here's how the episode is described: "Henry and Jo’s murder investigation of an ex-con, who is being framed for a jewelry story heist, reveals a special connection between the victim and Jo’s late husband, Sean, who was an assistant district attorney. Jo’s evocative memories reflect her warm and wonderful relationship with Sean, which become almost too painful for her to bear. Flashbacks trace Henry’s life to 1816 London where he ends up in jail. Incredibly, a priest, who is his cell mate, gives Henry a second chance at life. Meanwhile, Abe attempts to snare a thief who he believes walked off with a 'priceless' antique from his store, and Henry is there to comfort Jo in her time of distress, on 'Forever.'"

Rees won a Tony Award for his performance in The Life and Adventures of Nicholas Nickleby and was nominated for his performance in Indiscretions and his direction of Peter and the Starcatcher. His stage credits also include Uncle Vanya, The Red Shoes and The Addams Family. He recently starred alongside Chita Rivera in The Visit at Williamstown Theatre Festival.

Visit abc.go.com/shows/forever for more information.