Cosmic observations indicate that the dark matter component of our universe is more than five times as abundant as ordinary matter. The halo of dark matter surrounding our own galaxy and streaming past Earth presents a source of these particles to study in terrestrial experiments with distinctive signal features. Within the field of experiments searching for WIMPs, a theoretical favored dark matter candidate, no definitive signals have been detected with only one exception. The DAMA experiments operating arrays of low-background sodium iodide claim a persistent, high-significance (>9 sigma), model-independent detection of dark via its annual modulation signature. For twenty years that claim has stood, now in significant tension with many other experiments, but no one has been able to execute a complete test of the same signal with the same target material. I will present the COSINE-100 experiment, which has been operating a low-background array of NaI(Tl) crystals at Yangyang Underground Laboratory in South Korea since 2016. Our recent results already contradict the standard dark matter interpretation of the DAMA signal and are building to the final model-independent test. A decades-old mystery finally stands to come unravelled.
