  We numerically investigate the optical response of slowly scaling linear
chains of mismatched silver nanoparticles. Hybridized plasmon chain resonances
manifest unusual local field distributions around the nanoparticles that result
from symmetry breaking of the geometry. Importantly, we find localization
patterns characterized by bright hot-spots alternated by what we term
\textit{dark} spots. A dark spot is associated to dark plasmons that have
collinear and antiparallel dipole moments along the chain. As a result, the
field amplification in the dark interjunction gap is extinguished for incident
polarization parallel to the chain axis. Despite the strong plasmonic coupling,
the nanoparticles on the sides of this dark gap experience a dramatic
asymmetric field amplification with amplitude gain contrast $> 2 \times 10^2$.
Remarkably, also for polarization orthogonal to the axis, gap hot-spots form on
resonance.
