And season 1 loses a lot, while watched out of order. Yes, this is a typical procedural, and therefore each episode stands very much on its own (apart from some longer arcs, but even then you don't get all that much confused). But season 1 is not only about plots and murders, no. Season one is very much about loss and grief and Mac Taylor.
(And I think that, even though I adore Flack the most, and regard him as my tv boyfriend, I love Mac so completely, I might be watching this series for him.)
"Blink", like no other CSI pilot, hits us with personal, introducing us to Mac Taylor, and telling us just this: his wife has dies in 9/11, he has not let go of her, he still carries the grief, and the pain.
He tells the comatose victim: he had discarded all of Claire's posessions, because the memories of her were too painful. But he could not let go of a beachball she blew, because her breath was still in it.
We also learn that he is suffering from a severe insomnia, an information repeated a few times over the season. In Crime and Misdemeanor, for example, Stella asks him what people do when they can't sleep. Mac's quick answer is 'Work', to which Stella replies 'No, what do normal people do?'. In Goodnight, Mother, he feels sympathy for the sleepwalking suspect, and she recognises a kindred in him, and it's not only the matter of both of them having troubles sleeping, they have also both lost someone they'd loved.
But also, the first body they found, is a woman wearing a wedding ring. Mac's comment on the scene is 'Someone out there is missing a wife.' At this point in the story we don't know yet that this applies also to him, but there is a poignancy in the scene, a detached sense of loss and grief. The woman is not immediately identified, and the quest for her identity is something that resonates in repetition throughout the season.
Post-9/11, New York's ME's office had been identifying the victims for a long while. In CSI:NY, notably, Hawkes evidently sleeps in the morgue (as evidenced in Blink at least), quite possibly dedicating most of his time to this task. One of the most prominent themes of the show reflects this, the quest for identity. And for giving peace to those left behind.
This is whom Mac has the most empathy for, those who had lost someone, those left behind. Someone is missing his wife. Parents are missing their son (as in the most identity-concentrated episode of the season, American Dreamers). The job of the CSIs is not only to find the killer, but also to find out what happened, to piece together a story, to give the family the answer. In Supply and Demand, among others, he makes sure that the father of the victim knows the story, knows what happened and why.
And giving the others the answers, helps him, in a way. In looking for the answers, and the whole story, again, Mac finds a peace of mind for himself. In The Closer, Stella notes that, on working Sullivan's case and reinvestigating the evidence, he seems like his old self, 'from before...'.
And episode later, Mac seems to be moving on with his life, walking out of the office for something that just might be a date. He says it might be the time. It is marked, significantly, by Stella taking off his tie, something she had suggested at the beginning of the season, but it wasn't the time before, not yet. It's worth noting, that the tie doesn't make an appearance again, it's open shirt collar from season two onwards. It's a small thing, but it is a symbol of Mac's progress. He might be letting go. Maybe he might be letting go of the beachball, too.
In the last scene of the first episode, he got off a cab at Ground Zero, solemn and grieving. In the last scene of the season, he gets off a taxicab, walking into a bar, to meet his semi-date. Full circle. He is still the workaholic, still the insomniac, still the same person. And yet.