Firefox Down (1983)
Mitchell Gant returns in this cunningly disguised sequel to Firefox. The book picks up the story at the very moment that the first book ended. Perhaps after seeing the movie Thomas realized that he'd left out the ending.
Gant's stolen MiG-31 has suffered damage and is fast running out of fuel. He has no option but to try and land the plane in the snow-covered wastes of Scandinavia. A frozen lake in Finland stands in for a runway, but after landing the aircraft the ice breaks and the plane sinks into the water. Gant tries to put as much distance between himself and the landing site as he can but he's soon captured by the KGB who want the plane back.
This book is a bit of a reunion for a lot of Thomas' recurring characters. Even some people who have been killed off are allowed to return as the action of this book takes place before the events of some others, notably Snow Falcon and Sea Leopard.
The KGB man Priabin from Firefox becomes a more important character as he's betrayed from a source he wouldn't have expected. The consequences of this will be evident in Winter Hawk.
This entertaining follow-up is notable for chunks of his earlier book Moscow 5000 turning up. In fact one character makes the transition only to suffer the same fate.