Read it through once

In doing so, he turned to the side of the house behind him, and saw the lady of whom he was thinking seated in a box with the Beauforts, Lawrence Lefferts and one or two other men. He had not spoken with her alone since their evening together, and had tried to avoid being with her in company; but now their eyes met, and as Mrs. Beaufort recognised him at the same time, and made her languid little gesture of invitation, it was impossible not to go into the box.