A simple numerical algorithm to localize intergrid boundary points and to interpolate unsteady solution variables across two-dimensional, structured overset grids is presented. Overset grids are allowed to move in time relative to each other. Intergrid boundary points are localized in a triangular stencil on the donor grid by a directional search algorithm. The final parameters of the search algorithm give the interpolation weights at the intergrid boundary point. Numerical results are presented for steady and unsteady viscous flow solutions over an airfoil undergoing a sinusoidal flapping motion. Computed flowfields demonstrate the accuracy of the method, and excellent agreement is obtained against the single grid solutions. The method is independent of numerical solution algorithms, and it may easily be implemented on any two-dimensional, single-block how solver to make it a multiblock, zonal solver with arbitrarily overset/overlapping computational grids.