Working at the company run by his in-laws, the son-in-law finds himself under the care of his mother-in-law, who handles the accounting. He always thought of her as a serious and upright woman within the family, but when she teases him, saying, "Are you interested in my breasts?" he can't resist any longer! They end up fucking in the office, just the two of them. But their office affair isn't enough, and they go home to the bedroom for more, where he cums inside his mother-in-law!