  CP violation beyond the Standard Model (SM) is a crucial missing piece for
explaining the observed matter-antimatter symmetry in the Universe. Recently,
the ATLAS experiment at the Large Hadron Collider has performed an analysis of
electroweak $Zjj$ production, thereby excluding the SM locally at 95\%
confidence level in the measurement of CP-sensitive observables. We take the
excess' interpretation in terms of anomalous gauge-Higgs interactions at face
value and discuss further steps that are required to scrutinize its origin. In
particular, we discuss the relevance of multi-boson production using adapted
angular observables to show how they can be used to directly tension the
reported $Zjj$ excess in a more comprehensive analysis. To connect the excess
to a concrete UV scenario for which the underlying assumptions of the $Zjj$
analysis are valid, we identify vector-like leptons as a candidate theory
consistent with the observed CP-odd Wilson coefficient hierarchy observed by
ATLAS. We perform a complete one-loop matching calculation to motivate further
model-specific and correlated new physics searches. In parallel, we provide
estimates of the sensitivity reach of the LHC's high luminosity phase for this
particular scenario of CP-violation in light of electroweak precision and Run-2
Higgs data. These provide strong constraints on the model's CP-even low-energy
phenomenology, but also inform the size of the CP-odd SM deformation indirectly
via our model hypothesis.
