Cancer therapies can eliminate specific tumors based on their genetic content. However, some cancer cells survive. How do they do it? Part of the answer lies in extrachromosomal DNA (ecDNA), an ace up the tumors’ sleeve to adapt and evade attack. Three simultaneous studies in the journal Nature lay all the cards on the table, revealing ecDNAs’ content, their origin, their inheritance, their influence in cancer, and a way to combat them.