Reinforcements have arrived.

After an anemic finish to a bruising summer for the movie business, there’s finally some fresh blood at the box office. Sony Pictures will unveil “No Good Deed,” a crime thriller with Idris Elba, through its Screen Gems label, while Warner Bros. is making a splash with “Dolphin Tale 2.” It’s not a moment too soon after a miserable Labor Day that saw the box office plunge 23.8% year-over-year.

“Both movies are starting to look relatively strong and both are aimed at different audiences,” said Phil Contrino, vice president and chief analyst at BoxOffice.com. “We’re looking at a genuine horse race.”

The two films couldn’t be more distinct and both cater to demographics that have been severely neglected by major studios of late — African-Americans and families with young children.

Look for “Dolphin Tale 2” to swim ahead of the competition by debuting to $20 million from 3,656 theaters. The lovable creatures were a hit when they dived into theaters in 2011, earning nearly $100 million and justifying production on this $36 million sequel. It’s one of the first films geared at children to premiere since “Planes: Fire & Rescue” bowed in July — one of only three major family pictures last summer, the others being “Maleficent” and “How to Your Dragon 2.”

“No Good Deed” is looking nearly as strong, according to tracking. The home invasion thriller about a woman (Taraji P. Henson) terrorized by an escaped convict (Elba) cost a modest $13.2 million to produce. It should make $18 million when it bows in 2,171 screens. The studio is leaning heavily on the appeal of its two leads, and has tapped them to promote the film using their popular Twitter feeds.

In a more limited rollout, Fox Searchlight will introduce “The Drop” into 805 theaters. The adaptation of a short story called “Animal Rescue” by Dennis Lehane stars Tom Hardy and the late James Gandolfini. Chernin Entertainment produced the picture.

Reviews for the film, which follows a bartender who gets caught up in money laundering, have been strong. The picture currently enjoys a 78% “fresh” rating on Rotten Tomatoes. If moviegoers like it as much as critics, it will do close to $2 million this weekend and could up being a solid indie hit.

The injection of a few new releases means that “Guardians of the Galaxy” will have to relinquish its crown after three straight weeks as top dog. It should pull in $7 million, which will push it over the $300 million mark domestically, making it the first film to pass that threshold this year. So in some ways, it’s still the king.