Men At Arms: (Discworld Novel 15) by Terry Pratchett
'Funny, wise and mock heroic . . . The funniest and best crafted book I have read all year' Sunday Express
The Discworld is very much like our own - if our own were to consist of a flat planet balanced on the back of four elephants which stand on the back of a giant turtle, that is . . .
'What's so hard about pulling a sword out of a stone? The real work's already been done. You ought to make yourself useful and find the man who put the sword in the stone in the first place.'
The City Watch needs MEN! But what it's got includes Corporal Carrot (technically a dwarf), Lance-constable Cuddy (really a dwarf), Lance-constable Detritus (a troll), Lance-constable Angua (a woman... most of the time) and Corporal Nobbs (disqualified from the human race for shoving).
And they need all the help they can get, because someone in Ankh-Morpork has been getting dangerous ideas - about crowns and legendary swords, and destiny.
And the problem with destiny is, of course, that she is not always careful where she points her finger. One minute you might be minding your own business on a normal if not spectacular career path, the next you might be in the frame for the big job, like saving the world . . .
The Discworld novels can be read in any order but Men At Arms is the second book in the City Watch series.