An aggressive contagious cancer has emerged in the Tasmanian devil, a carnivorous marsupial endemic to the island of Tasmania. Known as Devil Facial Tumour Disease or DFTD , the disease is characterised by the rapid growth of large and disfiguring tumours around the face and neck of host devils, causing close to 100% mortality and rapid decline of the Tasmanian devil population. Naturally occurring contagious cancers, where tumour cells pass between individuals, are rare as the vertebrate immune system is very good at detecting and destroying foreign cells, just as it detects pathogens. We have been investigating how DFTD cells so successfully evade the host devil immune system, allowing the tumour cells to pass between devils and quickly establish new tumours. Based on these studies we are developing a vaccine that could rescue the Tasmanian devil in the wild and our findings may also have implications for understanding other advanced, drug and immunotherapy resistant tumours.