When "Hawaii Five-0" returns, viewers will find McGarrett and Danny seeking the help of FBI profiler Alicia Brown (Claire Forlani) to track down a suspect dubbed as the "Chess-Piece" killer.

"Hawaii Five-0" will feature an overarching storyline in Season 7. As revealed in the premiere's plot synopsis, the mysterious "Chess-Piece" killer will be known as a vigilante who puts chess pieces in their mouths as part of his modus operandi. When McGarrett and co. begins investigating the case, the team will make it their mission to stop the unidentified threat to combat fear among tourists.

The vigilante will prove to be more efficient in hiding from authorities. In the second episode, McGarrett and Danny will seek expert assistance from retired FBI profiler Alicia Brown - who has spent her life examining the behaviors of criminals. At first, it seems that Brown will take down the job on the initial offer.

It is not until the third episode of "Hawaii Five-0" Season 7 that Brown finally agrees to join Five-0's hunt, after finding a body in her bed. As to whether or not Brown's expertise will speed up the team's investigation and nail down the bad guy is yet to be determined. On a case like this, casualties are always expected to unfold.

"Hawaii Five-0" stars Alex O'Loughlin, Scott Caan, Daniel Dae Kim, Grace Park, Masi Oka, Chi MCBride and Jorge Garcia. The Season 7 premiere, titled "Makaukau 'oe e Pa'ani?" (Ready to Play?) will air on Friday, Sept. 23 at 9PM on CBS.