Heather and Arizona O'Neill are more than just mother and daughter — they're creative partners, storytellers and travel companions. Their latest collaboration, a novel called “Valentine in Montreal,” is already an instant bestseller. Heather wrote the book, which was first published in weekly installments in the Montreal Gazette, and Arizona illustrated it. The mother-daughter duo join Tom Power to tell us what it's like working together and why the Montreal subway system plays a special role in their relationship.