While the world celebrates William and Kate's wedding, one man, unstable and obsessed with the late Princess Diana, harbours a grudge against Camilla, Duchess of Cornwall. As his mental state deteriorates so his cunning grows. Seeing himself as 'Diana's avenging angel' he fools New Scotland Yard and gets onto the royal wedding route with a gun.

Only a disgraced royal cop and a wild, girl paparazzo can track the madman in the crowd down as Camilla and Charles, in the Australian State Coach, progress the Mall in the wedding procession...