Fans are days from away the premiere of "Hawaii Five-0" season 7, and spoilers about the new season pile up with new details on the second and third episode of the installment.

It looks like the team will be facing serious danger early in the season. The synopsis for the second episode "No Ke Ali'i Wahine A Me Ka Aina (Mother and Son)" reveals a highly dangerous criminal.

In "Hawaii Five-0" season 7, episode 2, McGarrett (Alex O'Loughlin) and Danny (Scott Caan) will take on the task of apprehending a "serial killer vigilante."

They start by asking the help of retired FBI profiler Alicia Brown to be played by Claire Forlani. It is unknown if she will be too thrilled to do so, but the third episode suggests she will be left with no choice anyway.

Titled "He Moho Hou (New Player)," the third "Hawaii Five-0" season 7 installment will catch up with Brown, who will be officially roped into the fray when she finds a corpse in her bed.

As per the synopsis of episode 3, this will force her to join McGarrett in looking for the party responsible, who they will come to refer to as the "chess-piece killer."

The criminal will begin his reign of terror in the "Hawaii Five-0" season 7 premiere. He is marked as a vigilante because his targets are serial killers.

He makes sure he leaves a signature after every kill by marking the dead bodies with an ivory chess piece, thus earning his infamous moniker from the authorities.

While all that happens, the rest of the team will work on stopping a terrorist from engineering a nuclear meltdown in Europe in "Hawaii Five-0" season 7.

The team will seek the help of MI-6 agent Harry Langford, played guest star Chris Vance. However, it may not be easy working with him. The synopsis teases that he is a "rogue" agent.

"Hawaii Five-0" season 7 premieres on Friday, Sept. 23, at 9 p.m. ET on CBS.