  We develop in components the superspace action obtained in arXiv:2110.07623
describing the first massive level of the open charged superstring in a flat
four-dimensional spacetime. In the absence of an electromagnetic background, we
show how the Rarita-Schwinger and Fierz-Pauli Lagrangians are retrieved for
spin-3/2 and 2, respectively. We then write different forms of the action in
the presence of the electromagnetic background. The resulting equations of
motion describe the propagation of fields of charged spin-3/2 and spin-1/2 on
the one hand, and spin-2, 1 and 0 on the other.
