Ahem - withdrawn
'The bank' is presumably some kind of temporary holding facility for as-yet unplaced aliens. They've turned the spy and brought his family over to the UK as a sign of good faith, but they haven't agreed terms with the defector so they haven't made final arrangements for accommodating his family. His opening bargaining position might be 'I'm a valuable asset and I've taken a huge risk. I want full indemnity, 24-hour protection for my family, and a detached house in Mayfair.' MI5's response might be 'Nonsense. We'll discuss what you can do for us and what we can do in return. In the meantime we'll look after your familly.' I have no idea what the 'again' is doing. It suggests to me (by its position) that the speaker is not a native speaker of English, in which case they may be using again to mean something that it wouldn't mean in the sentence 'They've put them in the bank again'.