Dark Sun is a World Book Day novella in the popular CHERUB series by Robert Muchamore.

[2] Following the previous book 'Mad Dogs', Greg "Rat" Rathbone is on an undercover mission to befriend the son of notorious activist, Kurt Lydon, and change the plan of his nuclear system.

Back at campus, Lauren Adams, Jake Parker and Andy Lagan are forced to do physical training on the assault course after messing around in front of a guest speaker.

Although overseen by volunteers James Adams and Bruce Norris, Andy is severely injured but still takes part in the mission, posing as Rat's Scottish cousin.

At the sleepover, Rat and Andy sedate George, Zhang and Lydon's wife and begin hacking into Lydon's laptop but are interrupted by George's older sister, Sophie.