Sheldon and Penny bond in Leonard's absence. Koothrapoli finds someone to share his heartache with. Elsewhere, while away at an out-of-town conference, Bernadette and Amy are hit on at the hotel bar.
McGarrett and the team investigate when a deadly hit-and-run involves a driverless car carrying heroin, and what could be a new means for delivering drugs. Also, Tani and Quinn are stuck with a pair of YouTubers (comedy duo Tom Allen and John Parr) who are brought on a ride-along with Five-0.
Jesse McCartney and his band are rehearsing in the hotel's basement, so London and Maddie disguise themselves as waitresses to meet them.
Cody is practising for the spelling bee that's to be held in the hotel, while Zack's scrounging money to play in the arcade. Cody finds himself competing against someone who's lent Zack money.
Cody is graduating top of the class from 8th grade, but Zack's done badly and must attend summer school - a fact he tries to hide from his parents.