Neutrinos undergo oscillations, shifting from one state to another in flight. But mounting evidence shows them oscillating into a new, undetectable, or “sterile” state. Earlier this year, one experiment reported the highest-precision measurement to date of a possible sterile-neutrino signal. Yet by late summer, another announced that it had firmly ruled out the sterile neutrino within the expected mass range. Now, Los Alamos, which was first to discover the neutrino anomaly in the 1990s, is working on three new detectors in the hope of solving the longstanding mystery and discovering something fundamentally new in particle physics.