I'm Sorry Grover: A Rosh Hashanah Tale is a Sesame Street storybook, one of a series of Shalom Sesame cross-overs in which the American Sesame Street characters learn about Jewish culture from the Rechov Sumsum Muppets. On the day before Rosh Hashanah, Brosh's wooly cap is missing. While Cookie Monster offers his detective skills, Brosh suspects one of his friends (especially Grover) has taken it. When Grover returns the cap (which Brosh had left behind), he apologizes, appreciating the High Holidays and striving to be a better friend.