A pier rode on the surface of the river, riding up and down on the tide, 
linked to the rim of the granite embankment by a hinged gangway. A shaggy black 
vessel was tied up to the pier, but it was completely unlit, visible only by 
its black shadow against the charcoal-gray water. After the chevalines had 
planted themselves and the Hackworths had dismounted, they were able to hear 
low voices coming from below.