“Hawaii Five-0” used its biggest guest star yet — its network cousin, the hit law enforcement drama “NCIS: Los Angeles” — to bump up its ratings Monday, according to Nielsen numbers released by CBS.

“Five-0” attracted 10.91 million viewers in a so-called “crossover episode” that featured “NCIS” stars LL Cool J and Chris O’Donnell flying to Hawaii to help solve a crime. The episode was the first part of a two-night plot that concluded Tuesday on “NCIS: Los Angeles.” In that episode, “Five-0” stars Scott Caan and Daniel Dae Kim traveled to the mainland.

The extra firepower wasn’t strong enough to win the hour for “Five-0,” which finished behind the 11.08 million viewers who tuned into ABC’s “Castle.” NBC’s “Smash” drew 5.34 million viewers.

“Five-0” fared better in its key target audience, adults 18-49. It drew 2.5 percent of the total viewing audience and 6 percent of those watching TV at the time, the network said. That put it ahead of “Castle,” which drew 2.3 percent of the total viewing audience and 6 percent of those watching television.

“NCIS: Los Angeles” typically finishes stronger than both of the Monday night competitors. It averages 16 million viewers and pulls in a 3.5/9 share, CBS said.