The introduction of a fascinating secret society, and its link to our hero (and twin) makes this a crucial segment of the series. In a way it reminded me of how early on the classic "Lost" TV series (long before it lost its way) provided tantalizing details that made its underlying mysteries more exciting.
The other important aspect of this particular story is the strong emphasis it gives to the cop character of Ilfenesh Hadera, who finally achieves virtually equal status with our hero in moving along the action and dominating the screen. Too many fine crime shows with the same underlying formula (strong lady lead with quirky, flamboyant male partner/helper) fail to ensure that the protagonists get equal time and end up with an imbalance, as is especially evident currently with both Alan Cumming in "Instinct" and Tom Ellis in "Lucifer" so dominant on screen by force of personality that their lady co-stars often disappear into the woodwork.