Set during a war between the 'Starmen (inhabitants of the planet Lilistar) and six-limbed insectoid creatures called the reegs, Now Wait for Last Year is the story of Eric Sweetscent, an organ-transplant doctor who gets wrapped up in Earth-Lilistar politics.

At the onset of the story, Sweetscent is the personal org-trans surgeon for Virgil Ackerman, the president of Tijuana Fur & Dye.

Ackerman invites Sweetscent to "Wash-35", a recreation of his boyhood native Washington DC in a simulated 1935 and his vacation getaway on Mars, where he announces an ulterior motive in the retreat.

Kathy arrives to inform her husband of her addiction, and in an effort to motivate him to find a cure she slips a pill of JJ-180 into his drink.

Without enough time to be furious, Eric slips a year into the future of an alternate world where his colleagues inform him that he disappeared the day Kathy came to visit.

However, aside from minor details, events in all observed universes seem to be moving in the same direction, and therefore, information obtained from one alternate world's future will most likely be applicable to another.

In Molinari's case he slips sideways in time under the drug's influence and is able to pull alternate versions of his present self into his own timeline and then keep them there.

Having learned the secret to Molinari's alter-aliases as well as confirming the feasibility of an alliance with the reegs, Eric takes a larger dose of JJ-180 which propels him further into the future.

Taking a fraction of a pill so as to not immediately return to his own time, Eric again ends up one year in his own future where the 'Starmen have occupied Earth after learning of the Terrans' defection to the reegs.

Now knowing the general future history of the next few years, Eric returns to his own time where his wife's mental condition is deteriorating every day.

Eric agrees and decides to stay with his wife despite the challenges presented by her condition, and in the closing paragraph is commended by the cab for being a 'good man'.