They were all crossing lines in their search for answers.

Peta Shepherd had already crossed the line. Archie Conn might know why, and Harry Roberts would cross lines to find him. Emily Freeman had crossed a line, leaving the US and moving to London to be with Len Stone, Peta’s friend, Archie’s nemesis. Her head was full of secrets; why was she leaving? Colonel Skinner would cross lines to discover why, and to keep the Brits off his back. Mick Edge would cross lines to discover why the Yanks were operating on his soil without his authorisation, and what Archie had learned from Peta Shepherd about the aliens she had once talked to.

And Archibald Franklin Conn? He had crossed many lines in his time - but the line he was about to cross would put him far beyond the pale.

In the end, all lines cross - and the outcome changes lives forever.