Crash into Christmas

‘What the fuck are you doing?’ Hermione mouthed from behind Roger’s beefy shoulder. But Malfoy just smiled brilliantly and slid off his stool, clapping Roger on the back and gathering their coats. Hermione heard him say something about the airport and a cab ride.
Roger turned toward a small corridor, gesturing at them to follow. Malfoy went quickly, but Hermione hung back. What the bloody hell was he playing at? Did he really mean to crash somebody’s Christmas party?