The Grey Envelope
Adventure #9 in the collection . First published in Thomson's Weekly News 03/16/1918
Heine is more than a little surprise at the unannounced visit to his office by Major Haynes. Haynes tells him that while Heine is of course totally innocent, some German agents were led to believe he was part of their network and they would be delivering an envelope with stolen top secret intel to be passed to another agent in Southport. Heine realized his only option was to pass any envelope to Haynes.