Colin Firth is officially the final piece in the casting puzzle for "Dorian Gray", or so says The Hollywood Reporter. The "Mamma Mia!" star has signed on to star opposite "Prince Caspian's" Ben Barnes in "Dorian Gray", the adaptation of Oscar Wilde's celebrated, "The Pictures of Dorian Gray".

This most recent stab at the Wilde classic is set to be directed by Oliver Parker ("Imagine Me and You"). The story centres on Gray (Barnes), a young man who becomes the subject of a mysterious portrait. As Gray embarks on a life of excess and scandal, the picture begins to age and morph, but Gray seemingly stays the same - immortal.

Firth will play Lord Henry Wotton, the aristocrat responsible for leading Gray down the hedonistic path.