In The Thumb Mark of St. Peter, a cloud of suspicion haunts the quiet town of St. Mary Mead when Mabel, Miss Marple's niece, finds herself the target of damning rumors. Her husband's sudden death—following a heated argument and a strange purchase of arsenic—has the entire village whispering about murder. Desperate and alone, Mabel calls upon her shrewd aunt, Miss Marple, for help. With her unparalleled intuition and attention to hidden details, Miss Marple uncovers unsettling clues: a cryptic phrase, 'a packet of fish,' and a trail that defies the obvious. As she peels back layers of village gossip and family secrets, Miss Marple faces a riddle that only someone with her insight could solve. Who knew that justice could come in the form of a kindly, unassuming lady from St. Mary Mead?