<p>What really happened in the hotel suite in Chongqing? The British businessman and go-between Neil Heywood arrives in Chongqing, where an"iron-blooded" police chief holds sway. The continuing true story of sex, death and Chinese politics, told by the BBC's former China Editor Carrie Gracie. </p><p>Producers: Maria Byrne and Neal Razzell 
Sound mix by James Beard.</p>

Murder in the Lucky Holiday Hotel: Episode 4

Twenty-five years on from the deadliest terror attack in history, BBC investigative journalist Jane McMullen asks why 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. 
 
McMullen investigates the hidden story of a man who helped two of the hijackers - and reveals a story that the US and Saudi governments have fought to keep secret.