The motion of a massive particle with intrinsic spin in a gravitational Einstein vacuum plane wave background is explored using the pole-dipole approximation to the Dixon multipole expansion for matter with compact support. Motivated by application to astrophysical processes the dynamical behaviour of the spin and particle motion is described by numerically solving a system of non-linear first order ordinary differential equations. Some results are displayed in a reference frame adapted to the transverse nature of a monochromatic polarised gravitational wave of arbitrary intensity.