A special episode on controversial plans for offshore oil drilling off Alaska's Arctic coast. Two decades after the Exxon Valdez spill, lingering oil is still found on beaches in Prince William Sound. How could offshore spills affect the lives of Inupiat Native Americans who depend on subsistence hunting and fishing? Native Alaskans find kinship with those who suffered from the Deepwater Horizon spill in the Gulf of Mexico. A passionate marine scientist uses a deep ocean submersible to study the impact of the Gulf spill hidden in the depths.