An official announcement about the collaboration was made in May 2007, although both filmmakers had to wait to film it: Spielberg was preparing "Indiana Jones and the Kingdom of the Crystal Skull" while Jackson was planning "The Lovely Bones". Spielberg had considered two books to become the main story, "The Crab with the Golden Claws" and "The Secret of the Unicorn", with the main plot eventually following the latter and its immediate sequel, "Red Rackham's Treasure". Jackson felt the former's story "wasn't really robust enough to sustain a feature film", but the filmmakers still included elements from the comic, such as the "Karaboujan" and the first meeting of Tintin and Haddock. Spielberg invited Edgar Wright to write the script for the film, but Wright was busy and instead recommended other names, including Steven Moffat. In October 2007, Moffat came as the screenwriter for two of the "Tintin" films. Moffat said he was "love bombed" by Spielberg into accepting the offer to write the films, with the director promising to shield him from studio interference with his writing. Moffat finished a draft, but was unable to finish another due to the 2007–2008 Writers Guild of America strike. He then became executive producer of "Doctor Who", leading Spielberg and Jackson (both of whom are fans of the show) to allow him to leave and fulfill his duty to the series. Wright then returned and agreed to take over the script while Joe Cornish, a fan of "Tintin" with whom Wright was working at the time, also worked with him. After two drafts of the script, Wright left in order to begin filming "Scott Pilgrim vs the World.", with Cornish staying on to finish the script under the guidance of Spielberg and Jackson.