This burglary mystery captures students' interest as they analyze how the mass-to-volume ratio of a liquid determines its density. As they observe the mass change while the volume remains constant, they begin to understand why the density increases. To analyze the data, students perform mathematical calculations, compare and contrast different liquids, and make accurate measurements. Participating in this hands-on, exploratory investigation allows students to use a trial-and-error approach that stimulates their thinking and leads to long-term retention of learning.