The Thea Sisters are five students at Mouseford Academy on Whale Island. They are adventurous, lively, fun mice, and they want to become journalists someday. Between lessons and friendship, life at Mouseford Academy is incredibly fabumouse. The Thea Sisters are surprised to find a mysterious love letter on campus. Determined to get the letter to the right mouse - and to figure out who wrote it - they print it in the student newspaper. More letters follow, and everyone at Mouseford wants to know who's writing the romantic notes. Can the Thea Sisters solve the mystery?