HBO's new series "I Know This Much Is True" features Mark Ruffalo in twin role

Actor Mark Ruffalo is set to star in and executive produce HBO's straight-to-series limited drama "I Know This Much Is True".

The six-episode series is based on Wally Lamb's New York Times bestseller of the same name, reported Variety.

It is described as a family saga that follows the parallel lives of identical twin brothers in an epic story of betrayal, sacrifice, and forgiveness, set against the backdrop of 20th century America. Ruffalo stars as twin brothers Dominick and Thomas Birdsey.

Derek Cianfrance serves as writer and executive producer as well as director.

The series brings Ruffalo back to HBO following his award-winning role in the Ryan Murphy telepic "The Normal Heart".