Series 9 Episode 6 discussion

[Tricky1]

Can someone tell me how the team knew where the russian/chinese spies were based?

Can someone also tell me how they managed to make it seem as if they were all at their desks as normal? They would have had to have sorted that before they blasted their way out of the grid but they were being watched so how could they have possibly looped the cctv or anything? also how did the bomb blast not alert the chinese/russians that something was up?

Absolutely great episode but they didnt really illustrate how the final outcome was reached!