  In this talk we summarize our latest results on the study of three-body
systems with explicit/hidden charm and with strangeness. In particular, we
focus on the $K D D $ and $K D\bar D^*$ systems, where a charm $+2$, isospin
$1/2$ and strangeness $+1$ state is found with a mass around 4140 MeV in the
former and a $K^*$ state, with hidden charm, at a mass around 4307 MeV is
obtained in the latter. Both states are predictions of our model and the
experimental confirmation of them would be important to understand the
properties of the strong interaction in the presence of heavy quarks.
