Megs -

Chuckie and Tony are right I think - it's in Jingo and it's around about the section where Vimes gets hot on the scent of who he
thinks tried to murder the 'wrong' (but morally rightful and peaceful) heir to the throne of Klatch (or wherever it was contesting the sovreignity of the mysterious new island territory) and decides to join Carrot in seeking out the dog-napped Angua despite being expressly ordered not to by Vetinari - who of course means Vimes to do exactly the opposite...
Something like that anyway!
The disorganiser I think comes up with this death prediction that Tony has said about, just before (or likely too late & after) Vimes makes the decision to follow the gung ho hereditary lords of Ankh - who have gone off to invade Klatch - to stop them making right prats of themselves
