Alex wakes up in a small room—the baddies have "handcuffed [him] to a radiator" (13.2). It's April 1, which means that the Stormbreakers are already on their way out; the good guys have lost.
Mr. Grin escorts Alex to Sayle's room, where he is plopped into a chair and handcuffed once again.
After some threatened torture, Alex spills the beans about everything—his real name, his relationship with MI6, and his current mission. Oh c'mon Alex, Jack Bauer would've never done that.
In true evil-genius fashion, Sayle explains his entire plan to Alex: The virus will be released when the Prime Minister presses the start button, infecting half of England with a hyper-deadly version of smallpox.
Sayle actually loved Britain when he first moved there—to him, it was "the heart of civilization" (13.25)—but things got bad almost immediately when Sayle was subject to racially charged bullying led by none other than the current prime minister. This led him to his current super-villainous path.
His word-vomit exhausted, Sayle tells Alex that Mr. Grin will return to the room to kill him in a moment. Oh good, thanks buddy.