  An anti-de Sitter background four-dimensional type N solution of the
Einstein's field equations, is presented. The matter-energy content pure
radiation field satisfies the null energy condition (NEC), and the metric is
free-from curvature divergence. In addition, the metric admits a non-expanding,
non-twisting and shear-free geodesic null congruence which is not covariantly
constant. The space-time admits closed time-like curves which appear after a
certain instant of time in a causally well-behaved manner. Finally, the
physical interpretation of the solution, based on the study of the equation of
the geodesics deviation, is analyzed.
