It follows in the success of the Young Bond and the Alex Rider series of books and films. M.I. High is recorded in high definition and is shown on the CBBC Channel and CBBC Outputs on BBC One and BBC Two. M.I. High is also shown on the BBC HD Channel. Repeats also frequently air in Australia on ABC3.
The series following the adventures of three Saint Hopes students, Blane Whittaker, Daisy Millar, and Rose Gupta (Series 1, Series 2); Oscar Cole, Rose Gupta and Carrie Stewart (Series 3, Series 4, Series 5); Dan Morgan, Tom Tupper and Aneisha Jones (Series 6, Series 7); and new agents Zoe (Series 6) and Keri Summers (Series 7) who work as undercover spies. The spies are led by M.I.9 agent Lenny Bicknall (Series 1-Series 2) and Frank London (Series 3-present), working undercover as the school caretaker.
The only spies left undercover are those still being trained, including those still in school. Their base is 230 ft below the school, accessed by a high-speed lift from the caretaker's store room, which changes the spies' clothing and hairstyles.
The identity of the villain across the series, the Grand Master, remains a mystery within the show, although a glance at the credits reveal that since series 2 he has been played by Julian Bleach. In series 1 his voice was performed by Kerry Shale and a "supporting artist" appeared on screen in shadow. M.I. High officially came to an end on 21st March 2011. Series 6 was revived in 2013 with Aneisha Jones, Dan Morgan, Tom Tupper, and Zoe and a new school called Saint Hearts then Series 7 with Aneisha Jones, Dan Morgan and Tom Tupper once again but this time with a new addition: Keri Summers.
- Series 1: Eastbury Comprehensive School's old site (Dawson Road site).
- Series 2: Christchurch School, Finchley, North London.
- Series 3: Old Blessed John Roche Catholic School for Boys in Poplar, East London.
- Series 4: Selhurst High School in Croydon.
- Series 5: Selhurst High School in Croydon.
- Series 6: North Glasgow College (now Glasgow Kelvin College)
- Series 7: North Glasgow College (now Glasgow Kelvin College)