A couple sit in their living room, pondering the path of the River Medway. They decide to find the river's source, and travel first by car and then by foot to a woodland water basin at Turners Hill. The film proceeds to document the river's course, filming it as it grows in strength and width when the tributaries Eden, Beult and Teise join it. Notable buildings which line its banks include Groomsbridge Place, Penshurst Place, and Rochester and Upnor Castles. Bridges, locks and weirs increase in numbers. The first signs of industry are seen at Maidstone where the Fremlins Ltd brewery, the Trebor Bassett sweet factory, and the Ford (?) motor car works on the bank of the river. Cranes, warehouses, factories, tugs and cargo barges populate the river as it approaches Rochester - the camera films from the top of a high crane filming as its grabber unloads cargo from a waiting boat. Flying boats stand idly on the river, whilst the paddle steamer 'Medway Queen' (?) traverses it. The journey ends with images of Royal Navy ships, including HMS Boadicea, anchored at the river's mouth - the final location before the open sea.