Highlights from the Twentieth Episode of Season 4 of Hawaii Five-0

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured Daniel Dae Kim as Chin Ho Kelly Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured Daniel Dae Kim as Chin Ho Kelly Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured (l-r) Grace Park as Kono Kalakaua , Alex O’Loughlin as Steve McGarrett and Masi Oka as Dr. Max Bergman Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured Alex O’Loughlin as Steve McGarrett Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured (l-r) Grace Park as Kono Kalakaua Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured (l-r) Scott Caan as Danny “Danno” Williams and Alex O’Loughlin as Steve McGarrett Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured (l-r) Scott Caan as Danny “Danno” Williams and Alex O’Loughlin as Steve McGarrett Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved

The investigation of a murdered pool cleaner leads Five-0 to uncover a possible terrorist cell of radicalized students who are plotting an attack on U.S. soil, on HAWAII FIVE-0, Friday, April 25 (9:00-10:00 PM, ET/PT) on the CBS Television Network. Pictured (l-r) Alex O’Loughlin as Steve McGarrett, Daniel Dae Kim as Chin Ho Kelly and Scott Caan as Danny “Danno” Williams Photo: Best Possible Screen Grab/CBS /©2014 CBS Broadcasting, Inc. All Rights Reserved