  We present a new model of string inflation driven by a blow-up K\"ahler
modulus of type IIb compactifications with a potential generated by string
loops. Slow-roll is naturally realized thanks to the fact that the blow-up mode
is a leading-order flat direction lifted by string loops which are unavoidable
and generate a plateau at large field values. We check that throughout the
whole inflationary dynamics the effective field theory is under control. We
perform a phenomenological analysis determining the exact number of efoldings
by studying the post-inflationary evolution. We determine the values of the
microscopic parameters which lead to agreement with CMB data, together with the
prediction of a tensor-to-scalar ratio of order $r\sim 10^{-5}$.
