Ico a horned boy, is taken by a group of warriors to an abandoned castle and locked inside a stone coffin to be sacrificed. A tremor topples the coffin and Ico escapes. As he searches the castle, he comes across Yorda, a captive girl who speaks a different language. Ico helps Yorda escape and defends her from shadow-like creatures. The pair make their way through the castle and arrive at the bridge leading to land. As they cross, the Queen, ruler of the castle, appears and tells Yorda that as her daughter she cannot leave the castle. The Queen destroys part of the bridge; although Yorda tries to save him, Ico falls off the bridge and loses consciousness.
Ico awakens below the castle and makes his way back to the upper levels, finding a magic sword that dispels the shadow creatures. After discovering that Yorda has been turned to stone by the Queen, he confronts the Queen in her throne room, who reveals that she plans to restart her life anew by taking possession of Yorda's body. Ico slays the Queen with the magic sword, but with her death the castle begins to collapse around him; he is hit by falling debris, breaking his horns, and he falls unconscious. The Queen's spell on Yorda is broken, and a shadowy Yorda carries Ico safely out of the castle to a boat, sending him to drift to the shore alone. Ico awakens to find the distant castle in ruins, and Yorda, in her human form, washed up nearby. She stirs.
In October 2012, It was reported that Paramount Pictures and Geo Animation Studios are developing a computer-animated film adaptation of Ico. It is being produced by Fumito Ueda and Kenji Kaido, the designers of Ico. It is directed by Chris Jones. However, in August 2013, production of the movie was shut down due to budget cuts and some technical and biological difficulties. That's because of the story being "too dark" for children. The cancelled project was later shelved in the Geo Animation Studios' Project Trash Storage room, with all the other cancelled projects ready to be thrown away into the furnace.
In November 2013, it was later announced that a computer-animated film based on Ico would be animated by 2BIG3k, the animation production company that was best known for the 2001 hit The Geo Team Movie, with pre-production services from Sony Pictures Animation. It will be directed by Henri Dosclz and produced by Adam Hargreaves and Kevin Misher. It was revealed that Fumito Ueda, the game's creator, will be involved in the film's production. In January 2014, it was announced that Terry Ward and David Bowers would write the script. On May 31, 2014, a cast was announced, with Dakota Goyo joining as Ico, Andrea Libman as Yorda, and Katherine Heigl as The Queen.
On July 4, 2014, it was announced that the film would be animated in CGI by Sony Pictures Imageworks (SPI), a visual effects and animation company that also works for Sony Pictures Animation. SPI created CGI animated sequences for the film from the company's VFX and animation production facilities at Culver City in California of the USA, and at Vancouver in British Columbia of Canada. In November 2014, it was announced that Michael Giacchino would be composing the film's music, making his second 2BIG3k film to be composed by Giacchino, the first being the 2012 film Geoshea Theft Auto 2.
Ico was originally scheduled to be released on February 27, 2015 by Universal Pictures in the US and Sony Pictures internationally, but following the announcement of the coinciding release of Universal's another film Everest (before pushing back to September 18, 2015), the release was pushed back to March 6, 2015. The film's trailer was released on August 15, 2014.