Tower Of The Winds by H.L. Dennis (Secret Breakers #4)

The Knights of Neustria's quest is clearer to Team Veritas now - but so is their understanding of the terrible enemy they are up against. People are going missing. No one at Station X is safe anymore. But there are still important truths to uncover. Which secret organization is protecting the work of the Knights of Neustria and do they know who is buried in the unmarked Shepherd's Tomb at Shugborough Hall? Will the story of the mysterious treasure ship 'The Covadogna' help the team of secret breakers discover more about the world described in the ancient coded Voynich Manuscript? And will every member of the team survive the race against time when the sinister Black Chamber chooses to leave them all a terrifying message?