"Bob Zemeckis and I had written three movies together, and we had always wanted to do a time-travel story. We'd just never figured out how. What turned the light on for me was coming across my dad's old high-school yearbook and thinking, "Would we have been friends if we'd been at school together?" All of us have that revelation when we understand that our parents were young once, too. That's a big moment. Then there is the message that we all have control over our destinies. I thought we could dramatise those two things."