(or at least, as much as I understood while I was half watching and half working on a fanfic with my back to the TV. I will watch it again later, and probably discover many of my facts in the following recap to be inaccurate.)
What looks, according to McGee, like an open and shut case involving a guy that shoots another guy turns out to be significantly more complicated when they can't find a bullet and it turns out the shooter is working for Homeland Security, and therefore Not To Be Bothered until they can definitively link him to the murder. This fact pisses off not only Gibbs, but his former boss/Mexico drinking buddy Mike Franks, whom he calls for information about how Russian Guy was a terrorist back in the day(s) of 1991 and probably still is. Franks decides to come all the way back to D.C., and despite a death threat from Russian Guy, refuses to cooperate when Gibbs orders him to a safehouse (his) under the watch of a bodyguard (Tony). Tony gets smashed over the head and Franks disappears, but while Gibbs turns his wrath on the Homeland Security agent who leaked secrets back in 1991, it turns out Franks didn’t so much come back to aid/follow the investigation as to secretly stalk the terrorist and shoot him dead. He almost gets shot dead himself in the process, but fortunately Gibbs finds him in time to save his life.
In other news, Ziva has not only finally grasped American idioms, but also the foolproof way to tell when Tony is lying (he looks down and to the left, as do many other people, which Catherine Willows told us on the first season of CSI). And for future reference, to take another cue from CSI, when bullets go missing from bodies, my delicate sensibilities would GREATLY PREFER it to be because they hit the heart and travel through the bloodstream to end up in the toe, not hit the stomach and get puked up.