Bootstrapping string theory on AdS${}_5\times S^5$

We make an ansatz for the Mellin representation of the four-point amplitude of half-BPS operators of arbitrary charges at order ${\lambda }^{-\frac{5}{2}}$ in an expansion around the supergravity limit. Crossing symmetry and a set of constraints on the form of the spectrum uniquely fix the amplitude and double-trace anomalous dimensions at this order. The results exhibit a number of natural patterns which suggest that the bootstrap approach outlined here will extend to higher orders in a simple way.