"Your ship is to carry out the trial of a new secret weapon, Bentley ... the success of which makes future submarine kills certain. Your own speed is of the essence ... less than thirty knots and the Wind Rode could be destroyed."
"Trouble is," Bentley said, "a merchantman's been torpedoed with the victorious Jap submarine perhaps lurking to complete the kill."
Randall was puzzled. "Submarines haven't been sighted so far west before, and then there's the large formation of enemy aircraft spotted dead ahead... how could the Japs travel so far without refuelling?"
Bentley dismissed immediately his own suggestion that they were shore based. "Obviously, there must be carrier out there ... it's too far from the Nicobars or Sabang." 
Irrespective of where it was, Bentley knew he had to destroy that refuelling point, do it completely, and with all the speed Wind Rode could muster to avoid destroying itself in the process...