NCIS covered up death and it was Gibbs's team! Everyone freak out!! Well actually it wasn't and we know they'd never do anything remotely illegal (slightly sarcastic). A blogger named Burns is killed, and he was about to meet a source that would spill the beans on NCIS.
If you want to know how the crime gets solved, watch the episode. The writers from Castle should take a page from NCIS and see how a great procedural works. The thing about Donald Bellisario shows is his amazing abilities to maintain the characters and their relationships while creating well-written crimes to be solved. It turns out the blogger was killed by a sandwich maker who was in an insider trader deal with the sailor along to lines of Strangers on a Train. It was a bit like Castle with the 2 perpetrators meeting at a location and conspiring together.
Ziva is still has no authorized for field work so she stayed in the office while everyone went out to have fun. It's clear she wants to be involved as much as possible, and at the end of the episode, we learn that she quit Mossad and wants to be an official member of NCIS. I highly doubt the process would be that easy, but I never expected a real portrayal of foreign relations anyways. There were several references to office fraternization which was way too obvious in reference to anything Tony and Ziva related. If the writers aren't going to be subtle, they should hold off on any development with them for a while.
McGee had a really random sidestory involving the polygraph person being interested in him. He is oblivious to it, but he's McGee. Nobody can blame him for being clueless.
There are jurisdictional problems and as always, Gibbs clashes with the police detectives which leads to great moments. The conflict isn't too prominent in this episode, but there was a hilarious scene when Tony and McGee get chased around by dogs and arrested, and have to be released by the head detective.