Official poster for Captain America: The Winter Soldier. Source: Marvel Entertainment.

Now we know why Walt Disney (DIS 1.12%) was so eager to order a full season of Agents of S.H.I.E.L.D. for its ABC television network. The Marvel movie machine needs the marketing for Captain America: The Winter Soldier.

The timing is inescapable. When Winter Soldier hits theaters on April 4, Agents should be nearing its season finale. A tie-in seems inevitable and ComicBook.com says we'll have one, citing a source that says the show will "tease and set up the S.H.I.E.L.D. of Captain America: The Winter Soldier."

What's that mean?

Honestly, it could be anything. But the trailer (below) suggests a strong tie-in to the "Civil War" story arc that stretched across the entire Marvel Universe and forever changed the texture of the "Captain America" comic book. Specifically, the star-spangled hero comes into conflict with Iron Man and S.H.I.E.L.D. over the prospect of requiring superhumans to register with the U.S. government. He'd later die in issue 25 of an epic 50-issue run that also introduced fans to the Winter Soldier. (Don't worry, he's back now -- this is the comics we're talking about, after all.)

Fans shouldn't expect the movie to tell the same story. But I also wouldn't be surprised if directors Anthony and Joe Russo, both professed comic book fans, borrow heavily from the source material.

Meanwhile, Agents is an entirely new property that's partly a callback to the 1960's superspy comic "Nick Fury, Agent of S.H.I.E.L.D."  and partly a spinoff of Marvel's The Avengers. The combo gives Marvel just enough grist to appeal to old fans who remember the comics and new ones who like the films.

It's a formula we've seen before in Marvel movies. The same one that propelled The Avengers to $1.5 billion at the box office and Iron Man 3 to $1.2 billion in grosses. Winter Soldier has a tougher hill to climb with its predecessor, Captain America: The First Avenger, earning just $371 million worldwide.

Thankfully, this time, Nick Fury will be around to help.

The new trailer for Captain America: The Winter Soldier. Sources: YouTube, Marvel Entertainment.