Disaster strikes as a specialised team of investigators struggle to find out the truth about a strange monolith which sends out an intercontinental signal.
A luxury cruise liner is requisitioned by the Greek government in an attempt to give safe passage to national treasures worth millions of pounds. The liner is attacked by an art collector who finds out about the plan. During the hijack the liner sinks to the sea floor and so begins a fight for survival as the remaining air begins to run out.