  It is generally expected that heavy fields are present during inflation,
which can leave their imprint in late-time cosmological observables. The main
signature of these fields is a small amount of distinctly shaped
non-Gaussianity, which if detected, would provide a wealth of information about
the particle spectrum of the inflationary Universe. Here we investigate to what
extent these signatures can be detected or constrained using futuristic 21-cm
surveys. We construct model-independent templates that extract the
squeezed-limit behavior of the bispectrum, and examine their overlap with
standard inflationary shapes and secondary non-Gaussianities. We then use these
templates to forecast detection thresholds for different masses and couplings
using a 3D reconstruction of modes during the dark ages ($z\sim 30-100$). We
consider interactions of several broad classes of models and quantify their
detectability as a function of the baseline of a dark ages interferometer. Our
analysis shows that there exists the tantalizing possibility of discovering new
particles with different masses and interactions with future 21-cm surveys.
