This interrupted case study teaches probability theory and transmission genetics through their application to the conservation of the endangered Florida panther. An endangered population is unlikely to survive simply due to its small population size. But a basic understanding of probabilities and transmission/population genetics reveals two additional problems with small population size: (1) lost genetic variation due to genetic drift decreases adaptability of the population and (2) increased homozygosity due to obligate inbreeding increases the expression of deleterious recessive alleles (inbreeding depression). These factors combine to create the phenomenon known as the extinction vortex--as a population size gets smaller and smaller, the likelihood of the population surviving decreases faster than the population size decreases, and the population is drawn ever-more strongly towards extinction. The case was developed as an interdisciplinary lesson in mathematics and biology for use in an introductory college-level probability and statistics course, but could also be used effectively in an introductory biology course in college (for non-majors or majors) or an advanced high school course in biology or probability.