Was Saudi Arabia involved in 9/11?

Twenty-five years on from the deadliest terror attack in history, thousands of grieving families are still fighting for answers.

In early 2000, two young Saudis arrived in San Diego. They had never been to America, spoke almost no English, and had no idea how to open a bank account or rent a flat. Within weeks they had done all of it. Twenty months later they hijacked a plane and crashed it into the Pentagon.

The BBC’s Jane McMullen has been investigating a man who helped two of the hijackers – and has revealed a story that the US and Saudi governments have fought to keep secret.

Producers: Mhairi Mackenzie and Xandra Ellin

Digital producer: Tom Bage

Mix: Travis Evans

Editor for The Global Story: James Shield

Editor for Intrigue: A 9/11 Story: Matt Willis

Senior news editor: China Collins

Photo: New York City skyline with Brooklyn Bridge in the foreground and the twin towers of the World Trade Center in the background.