Loyalty program Smiles, which works with Brazil's Gol airline, and its agency FCB Brazil have leveled up rewards program marketing with "Trip Book Smiles," an e-book whose contents change depending on where you are when you're reading it.

The agency, known for its inventive digital ideas like the 2014 mobile Grand Prix-winning Nivea sunblock campaign, tapped top Brazilian author Marcelo Rubens Paiva to write a novel about a fortysomething couple, Theo and Maria Manoela, who ditch their run-of-the-mill lives to travel back to where they honeymooned years earlier. But depending on where the reader is experiencing the book, that location could be Paris, Rome, Lisbon, Buenos Aires or New York.

The campaign is part of a broader effort from the client, "365 Reasons to Smile."