Mark Ruffalo is returning to HBO — this time for an all new limited series.

According to Deadline, HBO has given the green light to an upcoming adaptation of Wally Lamb’s bestselling book, I Know This Much Is True.

The adaptation will run as a limited drama series comprised of six episodes and stars Avengers: Infinity War vet Mark Ruffalo, who will be playing not one, but two different characters.

The actor, who last worked with HBO on the Emmy Award winning film, The Normal Heart, will play identical twin brothers Dominick and Thomas Birdsey in the upcoming adaptation.

The story is set in 20th century America and follows the parallel lives of both brothers. Pegged as a family saga, the series promises “an epic story of betrayal, sacrifice, and forgiveness.”

Behind the camera, I Know This Much Is True will be written, directed, and executive produced by Derek Cianfrance. The director’s past credits include 2010’s Blue Valentine (starring Ryan Golsing and Michelle Williams), and 2012’s The Places Beyond The Pines, starring Gosling and Eva Mendes.

In addition to starring as both brothers, Ruffalo will also be serving as executive producer alongside author Wally Lamb, and Ben Browning, Glen Basner, Gregg Feinberg, and Anya Epstein.

There’s currently no word on when HBO will premiere I Know This Much Is True.