  Calcium rich gap transients represent an intriguing new class of faint and
fast evolving supernovae that exhibit strong [Ca II] emission in their nebular
phase spectra. In this paper, we present the discovery and follow-up
observations of iPTF 16hgs -- an intermediate luminosity and fast evolving
transient that exhibited a double peaked light curve. Exhibiting a typical Type
Ib spectrum in the photospheric phase and an early transition to a [Ca II]
dominated nebular phase, we show that iPTF 16hgs shows properties consistent
with the class of Ca-rich gap transients, with two interesting exceptions.
First, while the second peak of the light curve is similar to other Ca-rich gap
transients (suggesting $M_{ej}$ of 0.4 M$_\odot$ and peak luminosity of $3
\times 10^{41}$ ergs s$^{-1}$), we show that the first blue and fast declining
(over $2$ days) peak is unique to this source. Second, with Integral Field Unit
observations of the host galaxy, we find that iPTF 16hgs occurred in the
outskirts (projected offset of $6$ kpc $ = 1.9 R_{eff}$) of a low metallicity
(0.4 Z$_\odot$), star forming, dwarf spiral galaxy. Using deep late-time VLA
and uGMRT observations, we place stringent limits on the local environment of
the source, ruling out a large parameter space of circumstellar densities and
mass loss environments of the progenitor. If iPTF 16hgs shares explosion
physics with the class of Ca-rich gap transients, the presence of the first
peak can be explained by enhanced mixing of 0.01 M$_\odot$ of $^{56}$Ni into
the outer layers the ejecta, reminiscent of some models of He-shell detonations
on WDs. On the other hand, if iPTF 16hgs is physically unrelated to the class,
the first peak is consistent with shock cooling emission (of an envelope with a
mass of 0.08 M$_\odot$ and radius of 13 R$_\odot$) associated with a
core-collapse explosion of a highly stripped massive star in a close binary
system.

High Energy Astrophysical Phenomena;Solar and Stellar Astrophysics