The invention relates to a plug (1), with a first plug-and-socket connector (5) and at least a second plug-and-socket connector (4) in which the first plug-and-socket connector (5) can be received, and with a surrounding housing (6) in which the second plug-and-socket connector (4) can be received non-displaceably in at least one securing direction (A). Furthermore, the invention relates to a mating plug (2) with a first mating connector (7) and at least a second mating connector (2a), in which the first mating connector (7) can be received. In order to facilitate the assembly of a plug-and-socket connector arrangement (3), provision is made according to the invention for the surrounding housing (6) to have a securing member (17, 18) which is designed to be able to be brought into engagement with the second plug-and-socket connector (4) and the first plug-and-socket connector (5) received in the second plug-and-socket connector (4), and by means of which the first (5) and second (4) plug-and-socket connectors can be fixed relative to the surrounding housing (6). For a mating plug (2), the object is achieved in that the first mating connector (7) is designed to be able to be constructed in modular fashion from a receiving module (7e) and a connection module (7f).