When rebellious foster kid Max is placed with the wealthy Mr. and Mrs. Hunter at their grand house, which is also a museum, in Amsterdam, he knows it's his last chance to make things work. Luckily, the Hunters are kind and welcoming, and the four kids they already foster make Max feel right at home. Finally, he's found somewhere he can be happy.But that same night Mr. and Mrs. Hunter mysteriously disappear... Max and his new siblings must band together to find out what's happened to them, starting with the hidden secrets of their own grand house, then following clues which will lead them on a quest through the streets, canals and tunnels of Amsterdam. At the same time, they must keep their parents' disappearance secret from the adults around them, or else social services will separate the kids and send Max to the grim Blackfriars Orphanage. They'll also need to fend off money-grabbing relatives, thwart an aggressive property developer who has his mind firmly set on owning the Hunter house, keep the family business running and all the while keep up with their school work! But these are the Hunter kids and they'll stop at nothing to bring their parents home and keep the family together.Ultimately, they'll uncover a plot against the Hunter family dating back hundreds of years and come face to face with a shadowy figure that has his sights set on their destruction.