Last year at the end of Season Three, Don (Rob Morrow) and Charlie (David Krumholtz) find the "Janus List," which is a list of all known spies. A comprehensive list of spies is a very convenient thing to have by itself, but one name on the list was particularly surprising. Colby Granger (Dylan Bruno) was on the list as being a spy for the Chinese. Personally, Colby is the last person on the team I would suspect as a spy except for maybe Megan (Diane Farr). Then they ended the season and expected us to wait an entire year to find out any more.
As it turns out (which you will find out in the first episode, so I'm really not giving anything away), Colby was a double agent who was really spying on the Chinese while pretending to be spying on the US to find out who all the real spies were. Confusing, no? Well anyway, this means that Granger does get to rejoin the team, but not everyone is happy to have him back. David Sinclair (Alimi Ballard) is quite upset with Granger for not telling him that he was working as a secret agent. Granted Granger wasn't allowed to tell anybody, but Sinclair feels that since he was his best friend, he should have known. It's going to be an uphill battle for Granger to get back in Sinclair's good graces.
The relationship between Charlie and Amita (Navi Rawat) becomes well established in this season. Obviously Amita knows Charlie's dad well by now and he approves of her. But is her family going to approve of Charlie? As many times as they postpone their visit, Charlie wonders if he's ever going to finally meet them. It really seems like as a series, Numb3rs only wants to deal with one or maybe two relationships at a time, so Millie (Kathy Najimy) just disappeared. We don't really find out what happened between her and Alan (Judd Hirsch). Don continues his pattern of relationship problems.
Now I'm sure with what I've said so far, you're wondering if Numb3rs has turned into a relationship drama. No, it definitely has not. It's just that you now need to watch all the episodes to keep up with everything in that department. What started as just one-off's has evolved into a wonderfully complex system that you need to keep up with if you want to understand everything. But you can still watch it here and there and get the same math and crime that you've come to love. If you ask me, I think they're steering a little more away from very complex math and trying to make it more understandable to the common person, but that's not necessarily a bad thing. True to the previous seasons, the end of the season definitely leaves you hanging to find out what is going to happen with the team and wondering who, if anyone, is really going to leave.
If you've never seen Numb3rs, you are missing out on a truly wonderful show. It is only getting better each year, so I recommend you go buy it now before you miss out on anything else!