Please Help!

Arc $AC$ is a quarter-circle with center $B$. The shaded region $ABC$ is "rolled" along a straight board $PQ$ until it reaches its original orientation for the first time with point $B$ landing at point $B^{\prime}$. If $BC = \frac{2}{\pi}$ cm, what is the length of the path that point $B$ travels? Express your answer in simplest form.