  The LHC discovery potential of heavy top partners decaying into a top quark
and a $Z$ boson is studied in the trilepton channel at 13 TeV in the single
production mode. The clean multilepton final state allows to strongly reduce
the background contaminations and to reconstruct the $T'$ mass. We show that a
simple cut-and-count analysis probes the parameter space of a simplified model
as efficiently as a dedicated multivariate analysis. The trilepton signature
finally turns out to be able to probe $T'$ masses up to $2.0$ TeV, when mixing
with first generation quarks is included. The reinterpretation in terms of the
top-$Z$-quark anomalous coupling is shown.
