David Morrissey has joined Emily Watson and Alex Etel in the new fantasy film, The Water Horse for Walden Media, Beacon Pictures, and Revolution Studios.

Jay Russell (Ladder 49) is directing the film based on the children's book by Dick King-Smith; according to The Hollywood Reporter, the film centers on a Scottish boy (Etel) who finds a mysterious egg on the shore of a loch. When the egg hatches, a water horse emerges, and the boy must find ways to protect the rapidly growing creature from those who see it as a threat. Morrissey will play Captain Hamilton of the Royal British Army whose troop has commandeered a small diner run by the boy's mother (Watson).

Robert Nelson Jacobs is adapting The Water Horse screenplay; production is set to begin next month; a 2007 release is scheduled.