However, Collins found that she preferred writing longer, more complex stories, and eventually decided to focus on writing novels. Her debut novel, "Gregor the Overlander", was published in 2003 and became a New York Times bestseller.
The success of "Gregor the Overlander" led Collins to write two sequels, "Gregor and the Prophecy of Bane" (2005) and "Gregor and the Curse of the Warmbloods" (2006). These books also became New York Times bestsellers and established Collins as a successful children's author.