The last instalment of this definitive account of Obama's presidency tells how Obama got re-elected for a second term and tried to tackle America's most intractable social problems - guns, immigration and race.

Episode four begins with president Obama's decision to launch the special operation into Pakistan, to catch Osama Bin Laden. Former CIA director Leon Panetta describes how Obama decides to go ahead despite odds no better than 50:50 and the strong misgivings of top advisors.

As his re-election campaign gears up, Obama has to make a tough choice on contraception - whether to side with the Catholic bishops, or health secretary Kathleen Sebelius and feminist activists. Obama chooses the women, and they contribute to his convincing election victory.

But soon after his re-election, America is shocked by the Sandy Hook massacre - 20 children are shot dead in a Connecticut school. The families of the victims and senior advisor Valerie Jarrett recall the president's attempts to strengthen gun legislation, but they are defeated by the gun lobby.

Obama's other ambitious reforms fared no better. Cecilia Munoz and Valerie Jarrett reveal how Obama worked with allies in Congress to create a bipartisan consensus on immigration but is defeated by the Republicans. The president can move forward only through executive action.

The background of the first black president is different from most African Americans'. Raised in Hawaii by white grandparents, Obama initially downplays racial issues but the shooting of black teenager Trayvon Martin provokes him to speak out. When Ferguson, Missouri, becomes a flashpoint of conflict between police and African Americans, Obama urges young activists to channel their anger into progressive change. Show less