What Happened in Berlin in ‘The Flight Attendant’ Season 2?

As Cassie continues to watch Will, he exchanges an envelope with the woman for a briefcase and then leaves. Cassie follows him as he leaves the hotel, and as he walks past a truck, there’s a major explosion. Luckily, Cassie wasn’t closer to him, as she’s already knocked unconscious by the explosion. She thinks it’s a bomb, but the CIA tries to convince her that it was a gas-line explosion. Regardless, it killed Will, and set off the series of events for the rest of the season.