St Hope's is on red alert - nits are sweeping the country! But when they infest the school and the pupils take on the characteristics of criminals, the teen spies realise these are no ordinary nits. The chief suspect is nit nurse Nora Braithwaite. Daisy realises the only way to stop the infestation is to destroy the gross mother nit on Nora's head.

An audacious diamond thief is on the loose, and Her Majesty The Queen entrusts her Crown Jewels to MI High for safekeeping. Chief suspect is Ben Wheeler, England Captain and former diamond collector. Rose and Blane suspect that Wheeler is using his 'Sling Your Bling' campaign as a front for the thefts, and divert him to St Hope's for further investigation.