In this paper, we present $\underline{\rm A}$cceleration by $\underline{\hbox{La}}$ser and $\underline{\hbox{Dyn}}$amics of charged particles (${\tt ALaDyn}$), a particle-in-cell code, to investigate the interaction of a laser pulse with a preformed plasma and/or an externally injected beam. The code, fully parallelized, works in 1-D, 2-D, and 3-D Cartesian geometry, and it is based on compact high-order finite-difference schemes ensuring higher spectral accuracy. We discuss the features, the performances, and the validation tests of the code. We finally present a preliminary application on a physically relevant case based on the PLASMON-X experiment of the CNR-INFN.