The release of the "World War Z" sequel is reported to be delayed. Reports claim that lead star Brad Pitt is set to film a new movie with fiancée Angelina Jolie.

It was initially reported that the sequel is slated to hit the theaters on Summer of 2015. Paramount Pictures, however, has not officially confirmed the date yet.

The sequel of Pitt's zombie-themed movie will be directed by Juan Antonio Bayona, the director of several award-winning films such as "The Impossible" and "The Orphanage."

According to KPopStarz, Bayona is scheduled to shoot "A Monster Calls," a movie adaptation of a novel by Patrick Ness, before working on the next WWZ film.

The production has hired Steven Knight May 2014 to pen the script for the sequel. Knight is a renowned writer has worked on the screenplays and scripts of movies and TV series including "The Detectives" and "Eastern Promises."

Viewers are expecting the movie to feature the re-surge of the eradicated zombies. In the first movie, Pitt's character can be heard saying that the war against the zombies has just begun--giving a hint that the sequel will focus on another plague-like battle against the undead.

Meanwhile, the production is still on the process of enriching its storyline. In a video chat with Variety, Pitt said, "We have so many ideas on the table from just the time we spent developing this thing and figuring out how zombie worlds work. We have so many ideas and so much information, we think we have a lot of stuff to mine from. We're going to do our best and see what we get out of it."

The production of the first movie went through a number of problems. There was a series of delays in the production, as well as complete re-write of some of the parts of the story. Nevertheless, they did not expect that WWZ will be a success in the box office. The movie grossed $533 dollars worldwide, enough to drive the production to come up with a sequel.