  The most general phenomenological model involving a lepton triplet with
hypercharge $\pm 1$ is constructed. A distinctive feature of this model is the
prediction of a doubly charged lepton, and a new heavy Dirac neutrino. We study
the phenomenology of these exotic leptons in both low-energy experiments and at
the LHC. The model predicts FCNC processes such as rare muon decays, which are
studied in detail in order to constrain the model parameters. All the decay
channels of the exotic leptons are described for a wide range of parameters. It
is found that, if the mixing parameters between the exotic and light leptons
are not too small ($>10^{-6}$), then they can be observable to a $3-5\sigma$
statistical significance at the 7 TeV LHC with 10-50 fb$^{-1}$ luminosity for a
400 GeV mass, and 14 TeV with 100-300 fb$^{-1}$ luminosity for a 800 GeV mass.
