Madge Meredith

When deep sea divers go too deep or stay down too long, they suffer from an excess of nitrogen in the bloodstream. The resulting narcotic effect is called "Rapture of the Deep." When a party of skin divers falls victim to the "rapture," one of them becomes homicidal.

Major Rogers plans for a decisive blow against the French army are thwarted when Ensign Towne is captured by Black Wolf's tribesmen. Rogers must rescue his young officer before the Indians can force him to reveal the Rangers attack plans.