The low-cost movie “Paranormal Activity 3” opened in first place at U.S. and Canadian theaters in the most successful debut ever for a horror film, generating $54 million for Viacom Inc.’s Paramount Pictures.

“The Three Musketeers,” from Summit Entertainment LLC, took fourth place in its debut with $8.8 million, researcher Hollywood.com Box-Office said yesterday in an e-mailed statement.

The “Paranormal Activity” films are among Paramount’s most profitable. The first, made for about $15,000, had $193.4 million in worldwide ticket sales, according to Box Office Mojo. The second cost $3 million and took in $177.5 million. The latest was made for $5 million, according to the Hollywood Reporter, and was expected to generate $39 million in opening weekend sales, Box Office Mojo estimates.

“This $54 million performance is totally unexpected,” said Paul Dergarabedian, president of the box-office division of Hollywood.com, in a telephone interview. “For some reason, this franchise resonates. This brand is so well-known that they just put the name out there, ‘Paranormal Activity,’ and the audience lines up.”

“Paranormal Activity 3” is a prequel to the first two films, explaining the origins of the supernatural terror that haunts two sisters and their families.

Like the other movies, the third installment is presented as footage from home-video cameras set up by the family to capture the source of strange occurrences. The movie features Sprague Grayden and Katie Featherston.