In 2003, his first two books in the "Mad Grandad" series for younger readers were released by the O'Brien Press of Dublin, followed by his first young adult novel, "The Gods and their Machines" in 2004. More "Mad Grandad" titles soon followed as well as two more young adult novels, "The Harvest Tide Project" and "Under Fragile Stone" (collectively known as the "Archisan Tales"). "The Harvest Tide Project" was actually the first novel McGann had written, but it was contracted as part of a three-novel deal, and his publishers chose to release "The Gods and their Machines" first.