The fourth season of NCIS is finally reaching adolescence. After evolving through six fairly predictable (though possessing flashes of fine television) episodes, the NCIS staff detonate a universe of intrigue (both professional and personal) with “Sandblast.” This is the episode where the interpersonal relationships blossom and transform from innuendo and speculation into kinetic powers with their own momentum.

A Marine Colonel Frederick Cooper (David Fabrizio) is playing golf with his son, Josh Cooper (Blake Bashoff) at the Army-Navy Golf Club the day before he is deploying to Iraq. The Colonel has a lay in a bunker; he tries to blast out of this with a sand wedge and instead is blasted by a booby-trapped explosive device. The subsequent investigation brings together Special Agent Leroy Jethro Gibbs’ (Mark Harmon) NCIS team with Army Lt. Col. Hollis Mann’s (Susanna Thompson) Army Criminal Investigative Division (CID), the latter of which has beaten Gibbs to the scene.

Jurisdiction at the scene is complex as the murder occurred at the Army-Navy Club, giving both CID and NCIS authority and a sturdy turf battle. Gibbs’ and Mann’s introductions are cool, reflecting Gibbs’ suspicious state of mind and old school attitude. However, the observer’s eyebrows should twitch. Mossad Agent Ziva David (Cote de Pablo) observed, “Gibbs just found his fourth ex-wife.”

The viewers finally see Special Agent Tony DiNozzo’s (Michael Weatherly) girlfriend, medical student Jeanne Benoit (Scottie Thompson). Benoit questions Tony on how he stayed single for so long. Tony claims commitment issues and Benoit is not buying, reasoning that Tony has not looked at one other woman in spite of the fact that ample comely ones have walked by. Coyly (would Tony act any other way?) he answers, “I am patiently waiting to find the right girl.” Benoit further probes if he will ever find her. “I am getting more and more confident by the day” is DiNozzo’s provocative response.

In another budding relationship, Mann pays Gibbs an unannounced visit at his house, much to his annoyance. Gibbs is finishing his boat by naming her “Kelly” after his dead daughter. Hollis makes conversation, ostensibly because she and Gibbs lead a joint investigation. Plowing too close to the cotton regarding the name Kelly, Mann is treated to the famous Gibbs silent stare. Among all of this intrigue, Gibbs and Hollis spend ample time inspecting one another’s anatomy. NCIS Director Jenny Shepard (Lauren Holly) questions Gibbs about his working relationship with Mann, foreshadowing a complex relationship triangle.

While all efforts to accumulate essential evidence continue to fail, Director Shepard reveals to Gibbs CIA intelligence pointing to a suspected home-grown terror cell revealed by a CIA informant. Gibbs is dispatched to a warehouse where he meets Mann and Tony discovers that the true target of a discovered bomb were the two investigative units. Gibbs and Mann clear the building for the bomb squad, except Ziva, with Tony tagging along, disobeys Gibbs to stay and disarm the bomb in order to protect evidence. During the humid tension of the bomb deactivation Tony and Ziva have the most deliciously flirting, tempting, titillating dialog exchange of all four seasons of the show. Tony is definitely conflicted regarding David and Benoit.