Wondering how to make the study of the immune system and infectious agents more relevant to your students' lives? The online adventure series, Medical Mysteries, can provide the context and motivation. The series combines the drama of television's "CSI" episodes with science to address several of the National Science Education Content Standards. This free teaching tool incorporates online games with classroom activities for middle school students. The virtual experiments engage students in analyzing data, interpreting charts and graphs, and drawing conclusions. (Contains 3 figures.) [Additional funding for these materials was provided by the National Institute of Allergy and Infectious Diseases.]