The finale of season four of AMC’s “Mad Men’’ was called “Tomorrowland.’’

The first episode of season five, an extremely satisfying two-hour edition premiering Sunday night at 9, is called “A Little Kiss.’’

There is so much promise in those titles, of bright futures and exciting new beginnings.

It is a crossroads at which the series’ lead character, ad man Don Draper (Jon Hamm), has found himself before, and always managed to navigate.

Change is definitely in the air for all of the employees of Sterling Cooper Draper Pryce - and the world around them - but the past won’t let go of any of them so easily. Whether it comes in the form of lovers, clients, identities, or ideals, the shadows linger and the characters alternately cling to them and shoo them away.

While 17 months have passed for viewers, the time jump on the show is not as dramatic.

The episode, written by series creator Matthew Weiner, is a model of efficiency and nuance.

It brings us up to speed with almost every major character (except Betty) in ways that bear no resemblance to bland exposition. Instead, puzzle pieces are dropped for assembly by the critically acclaimed show’s devoted fan base: ages of children, lengths of maternity leaves and hemlines, the composition of people and signs on picket lines, milestone birthdays, and casual mentions of the status of relationships are all there to help calculate where in the ’60s we have landed. It’s the kind of fun, dramatic math at which “Mad Men’’ excels, going for the implicit rather than the explicit in service of character and story.