  We present dark tridents, a new channel for exploring dark sectors in
short-baseline neutrino experiments. Dark tridents are clean, distinct events
where, like neutrino tridents, the scattering of a very weakly coupled particle
leads to the production of a lepton--antilepton pair. Dark trident production
occurs in models where long-lived dark-sector particles are produced along with
the neutrinos in a beam-dump environment and interact with neutrino detectors
downstream, producing an on-shell boson which decays into a pair of charged
leptons. We focus on a simple model where the dark matter particle interacts
with the standard model exclusively through a dark photon, and concentrate on
the region of parameter space where the dark photon mass is smaller than twice
that of the dark matter particle and hence decays exclusively into
standard-model particles. We compute event rates and discuss search strategies
for dark tridents from dark matter at the current and upcoming liquid argon
detectors aligned with the Booster beam at Fermilab -- MicroBooNE, SBND, and
ICARUS -- assuming the dark sector particles are produced off-axis in the
higher energy NuMI beam. We find that MicroBooNE has already recorded enough
data to be competitive with existing bounds on this dark sector model, and that
new regions of parameter space will be probed with future data and experiments.
