The title says it all

Lauren has changed. After six weeks in San Diego California, she has come back with short hair, a new tan, and a hard distancing shell that will be almost impossible to crack. She has put up her walls and may never let anyone in again. Will Barney give up and move on? Or will he have to 'wait for it'?

Barney Stinson is...a pig to say the least. He's slept with countless girls, always wears a suit, and lives his life by his beloved playbook. He is also never one to back down from a challenge. When Barney is challenged by Lily to get a certain girl at the bar to go home with him, he is surprised to find that the charms he's used many times before aren't working. A simple petty bet brought the crew a new friend. But what if she's more than that? What if this girl can actually change Barney Stinson?