I think the theme of this work could be aptly summed up in one word: connections. Sam has to go through a process of repeating a single day until she realises how intimately she is connected with those around her and the kind of choices and decisions that they make. Sam has to learn the hard way how her actions as she follows along behind Lindsay and allows herself to be led on by her impact others, and how they have profound consequences that she is desperate to avoid. Consider the following comment which Sam utters out of a sense of desperation as she tries to escape her seemingly endless repetition of days:

It feels like I’ve been caught up in some enormous web and every way I turn I see that I’m stuck to someone else, all of us wriggling around in the same net. And I don’t want to know any of it. It’s not my problem. I don’t care.

When Juliet commits suicide, Sam is able to see and accept the various decisions and choices that have led her to take her life and she begins to realise how a series of bad choices on her part has led her to be culpable just as Lindsay is culpable. Fortunatley, repeating one day gives Sam the opportunity to go back and right her various wrongs. This novel thus presents what happens as being the outcome of a series of choices that we make. We are all connected with ties that draw us together much closer than we would otherwise think.