It's the following afternoon and Alex is being debriefed by Mr. Blunt and Mrs. Jones; they tell him that they're covering up the previous day's events, especially with Sayle still on the loose.
As agreed, MI6 will ensure that Alex gets to keep his home and that Jack will be able to stay in the country. They're also sure to mention that they'll contact him if "another situation arises" (17.33).
Alex leaves and hails a cab. Unfortunately, though, the cab driver is Herod Sayle. And he has a gun.
Sayle drives Alex to a tall skyscraper and brings him to the roof; there's a helicopter hovering above.
Sayle yells at Alex, telling him that he's going to kill him before he escapes, when suddenly, Sayle collapses—he's been shot.
The helicopter lands and Yassen Gregorovich emerges "holding the gun that had killed Herod Sayle" (17.63).
Yassen tells Alex that he had instructions to kill Sayle, but no such instructions regarding Alex. As he walks back to the helicopter, Alex says that he'll kill Yassen for what he did to Ian Rider. Yassen laughs.