Some large N gauge theories in higher dimensions, known to be dual to string theories, were shown to be integrable in the planar limit. A detailed mapping to 2d integrable field theories was devised. While a lot is known about the spectrum of these theories, the computation of physically significant correlation functions is still under way. A particularly simple example of four point function of operators with large charges was studied in detail by Frank Coronado, and the answer was given two years ago in the form of a Fredholm Pfaffian/determinant. In this talk I will present the ingredients and the main results of this (old) work done in collaboration with Ivan Kostov and Valentina Petkova. [The talk will also be streamed online, please ask the organizers for the link.]