sleepoverclub.com (The Sleepover Club, Book 44)

Join the Sleepover Club: Frankie, Kenny, Felicity, Rosie and Lyndsey, five girls who just want to have fun – but who always end up in mischief.
When the girls decide to secretly design a website for Lyndz’s brother Tom’s band, they accidentally lose the only disk with a copy of the band poster on it – and it falls into the hands of a mystery e-blackmailer!