Damien Darhk will launch an attack on Oliver Queen's holiday party in the midseason finale for Arrow, a newly-released synopsis from The CW has revealed.

When Oliver -- who tonight dedicated himself to fighting HIVE out in the open -- makes a move against the organization, Darhk will "retaliate in a brutal manner."

Could this play into who ends up in that mysterious gravesite?

“Dark Waters” — (8:00-9:00 p.m. ET) (Content Rating TBD) (HDTV)

OLIVER TAKES ON HIVE — After the city is attacked again, Oliver (Stephen Amell) makes a bold move against HIVE. Malcolm (John Barrowman) checks in on Thea (Willa Holland) and leaves her with a warning. Things take a horrible turn when Damien Darhk (guest star Neal McDonough) retaliates in a brutal manner at Oliver’s mayoral holiday party. John Behring directed the episode written by Wendy Mericle & Ben Sokolowski (#409). Original airdate 12/9/2015.