  Gravitational lens modeling is presented for the first discovered example of
a three-component source for which each component is quadruply imaged. The lens
is a massive galaxy member of the cluster Cl J0152.7-1357 at z ~ 0.84. Taking
advantage of this exceptional configuration and of the excellent angular
resolution of the HST/ACS, we measure the properties of the lens. Several
parametric macroscopic models were developed for the lens galaxy, starting from
pointlike to extended image models. For a lens model in terms of a singular
isothermal sphere with external shear, the Einstein radius is found to be R_{E}
= (9.54 +/- 0.15) kpc. The external shear points to the cluster's northern mass
peak. The unknown redshift of the source is determined to be higher than 1.9
and lower than 2.9. Our estimate of the lensing projected total mass inside the
Einstein radius, M_{len}(R < 9.54 kpc), depends on the source distance and lies
between 4.6 and 6.2 x 10^{11} M_{Sun}. This result turns out to be compatible
with the dynamical estimate based on an isothermal model. By considering the
constraint on the stellar mass-to-light ratio that comes from the evolution of
the Fundamental Plane, we can exclude the possibility that at more than 4 sigma
level the total mass enclosed inside the Einstein ring is only luminous matter.
Moreover, the photometric-stellar mass measurement within the Einstein radius
gives a minimum value of 50% (1 sigma) for the dark-to-total matter fraction.
The lensing analysis has allowed us to investigate the distribution of mass of
the deflector, also providing some interesting indications on scales that are
larger and smaller than the Einstein radius of the lens galaxy. The combination
of different diagnostics has proved to be essential in determining quantities
that otherwise would have not been directly measurable with the current data.
