According to Entertainment Weekly, Howard's scenes will take place in the flashbacks of Danno (Scott Caan) as he recalls his former life as a New Jersey cop. And apparently, the two characters are set to clash.
There's also talk that Howard may have been cast as a replacement for Ving Rhames, as reports earlier this month confirmed that Rhames would star in an episode with the same description. Haven't seen confirmation of this yet, but it's certainly possible.
Hawaii Five-0 returns to CBS on September 24.