  We discuss properties of interpolating geometries in three dimensional
gravity in the presence of a chiral anomaly. This anomaly, which introduces an
unbalance between left and right central charges, is protected under RG flows.
For this simple reason it is impossible to gap a system with such an anomaly.
Our goal is to discuss how holography captures this basic and robust feature.
We demonstrate the absence of a mass gap by analysing the linearized spectrum
and holographic entanglement entropy of these backgrounds in the context of
AdS$_3$/CFT$_2$.
