Will star as half-god hero's mom

Whoa, mama.

Catherine Keener has signed on to play mom to the half-human, half-god Percy Jackson in, well, "Percy Jackson."

According to The Hollywood Reporter, Keener will play the sort of mother who's always kept her son fully rooted in the human world, which of course means she's soon abducted by the God of the Dead. In the books, Jackson (whose first name echoes that of Greek hero Perseus) is also searching for the stolen thunderbolt of Zeus.

Pierce Brosnan and Uma Thurman were cast as a centaur and Medusa, respectively, in late March.

Keener, 40, will co-star this year in "The Soloist."