No one knows what Saudi Aramco is worth. Oil and gas experts estimate Saudi Arabia’s state-owned energy giant could be worth “trillions of dollars”, making it easily the world’s biggest company. But Montreal-based artist Hajra Waheed, who has solo shows in The Mosaic Room in London (Sea Change, until 21 May) as well as the Baltic Centre for Contemporary Art in the north of England (The Cyphers, until 30 May), knows more than most about the ultra secretive company. She grew up in one of the company-owned and carefully guarded communities in Dhahran. Needless to say, news from the outside world was carefully controlled. “I learned to read between the lines,” Waheed says, adding that it was at the end of the Cold War era. It’s a skill that she puts to good use in her drawings, collages, videos and sculpture. The Cyphers show at the Baltic has travelled from Berlin (where else?). Recalling documents and images from classified files or parts of a spy satellite that has fallen to earth, it all reminds us that the spooks are watching everything that moves on land, sea and air.