Roberta works at a bookshop and, while sorting through some of her grandmother's books, she comes across a letter that throws her family's history into doubt. It seems to imply that Roberta's grandparents were never married and that her grandfather, Jan Pietrykowski, died later than she was told. Roberta is shaken by the news, but feels that she cannot ask her father about it because he's in ill health, and her grandmother Dorothea, at 110, slips in and out of lucidity. Interspersed with Roberta's contemporary story is that of Dorothea's and Jan's during World War II. What happened all those years ago between them? Mrs. Sinclair's Suitcase was an enjoyable read that is similar to Lauren Willig's stand-alone novels.