Every second of our lives, we are under attack. As an indispensable part of our immune system, T cells protect us from the onslaught of bacteria and viruses and also from cancer. What happens at a molecular level when T cells detect suspicious activity in the body? In a recent paper, Mario Brameshuber and co-workers from our lab and from the Medical University of Vienna revealed that the immune receptors of T cells operate in unsuspected ways. While most experts in the field reasoned that T cell receptors must interact with one another for effective immune-signaling, this study published in Nature Immunology, opens an external URL in a new window shows that the T cell receptors act alone.