The Hawaii Five-0 season 4 will wrap up on May 9 with the finale.
Ian Wright (Nick Jonas) returns, and kidnaps Grover's daughter. The official description says that Grover is then forced to help steal $100 million in order to get her back.
Grover is forced to break some rules, giving him new perspective, showrunner Peter Lenkov said.
He starts off the season looking at what McGarrett's doing as being unorthodox, and it's everything he hates in a cop," Lenkov told TVGuide. "Now, Grover's put into a situation where he's got to act the same way. I think he sort of learns a lot about himself and gains a new respect for McGarrett."
Wo Fat (Mark Dascascos) also escapes from prison and heads back to Oahu. His return will be featured in a pivotal scene.
"The end is going to be a big shocker," Lenkov said. "And I don't think anybody is going to see it coming,"
Due to strong ratings, Hawaii Five-0 has already been renewed for a season 5.
The premiere date for the new season hasn't been announced yet.