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The Castle star will play Greek god Hermes in the follow-up to 2010's Percy Jackson & the Lightning Thief, according to The Hollywood Reporter.
Actor Dylan Neal played Hermes in the original film.
Logan Lerman will reprise his role as the titular Percy Jackson, while Alexandra Daddario, Brandon T Jackson and Jake Abel are expected to return as well.
In early March, Mary Birdsong, Yvette Nicole Brown and Missi Pyle joined the sequel. The trio will play the Fates in the film.
Percy Jackson: Sea of Monsters is scheduled to be released in 2013.
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Watch the trailer for Percy Jackson & the Lightning Thief below:
