In the last episode of "NCIS," the team had to deal with cyber threats. It was later when they realized that these cyber threats are actually linked to a terrorist group called The Calling. 

In the upcoming episode, The Calling is discovered to be recruiting children through the Internet to do terrorism work around the world.

Episode 23 is titled "The Lost Boys" and the official synopsis goes:

The NCIS cyber case turns into a united global effort after evidence confirms 'The Calling,' an international terrorist group that recruits children through the internet, has been purchasing S-bombs off the black market."

Based on the previews, "The Lost Boys" may actually refer to the boys being recruited by the terrorist group. In the first preview, Gibbs is seen at the site of the bombing and he is investigating what happened. He then notices that a child is observing him. He tries to talk to the kid, but the latter runs away.

In the second preview released, the team is talking about the evidence proving that Samar killed Wilt. Also, they talk about the child Gibbs saw on the street and believe that the child is actually sharing details with The Calling through a chat room named Dark Web. 

The story of "The Lost Boys" lays the groundwork for the finale episode airing next week. The NCIS team continue the hunt and, according to spoilers, there is an emotional death in the finale. 

Moreover, there are two characters returning in this episode. Actor Matt Jones again plays the role of Special Agent Ned Dorneget. The other one is actor Tamer Hassan who plays Agah Bayar, the holder of an important piece of information that the NCIS team needs.

"NCIS" airs "The Lost Boys" on May 5 on CBS.