Tunnels of Tyranny - #4 Moose Jaw Time Travel Adventure by Mary Harelkin Bishop
In this fourth book of the bestselling Canadian kids’ and teens’ series, 16-year-old Andrea and her 11-year-old brother Tony travel back in time yet again to the tunnels below 1920s Moose Jaw. This time, they are on a special mission for their grandfather and need to find something fast! There are threats and scary encounters with people wearing eerie white hoods. What must Andrea and Tony do to stop these strangers from carrying out their hateful plans?