Lewis Allen directed and Richard Sale wrote Suddenly, which features Frank Sinatra, Sterling Hayden, James Gleason, Nancy Gates, Kim Charney, and Christopher Dark in the cast. David Raksin composed the music, and Charles G. Clarke was responsible for the cinematography. The film centers on a small American town preparing to host a presidential visit. However, this event draws the attention of assassins who take the Benson family and their friends hostage because their home provides an ideal vantage point for a sniper aiming at the President. There’s a saying: show me someone with feelings, and I'll show you a sucker. Sinatra apparently wasn’t comfortable with his role in Suddenly, even before he requested it be withdrawn from distribution after the assassination of JFK in 1963. Concerns arose within his camp that portraying such an unsavory character could damage his public image, especially so soon after his Oscar-winning performance in From Here to Eternity. Sinatra attempted to redeem the character by reversing roles in The Manchurian Candidate (1962), but events changed considerably following November 22nd, 1963. This history gives Suddenly a level of interest it doesn’t really require, because it's an engaging thriller that can stand on its own merits and benefits from Sinatra’s excellent performance—one of his finest, in fact. It’s regrettable that the film was unavailable for viewing for quite some time, as it deserves greater recognition. The filmmakers present a hostage situation with a noir sensibility through the conspiracy angle, incorporating elements like paranoia, a family facing danger, and the classic noir trope of a returning soldier deeply affected by war. John Baron (Sinatra) has a taste for killing, and he’s taunted by Sheriff “Tod” Shaw (Hayden) about his methods and motivations; Baron insists that he's a Silver Star recipient who killed 27 German soldiers, but this doesn’t obscure the fact that he’s willing to kill the President for money. To him, the President is simply a target of no particular significance—Baron is truly detached, and Sinatra delivers an intensely nervous and tightly wound portrayal. Sinatra is supported by Hayden in one of his characteristic strong, masculine roles, while Gleason excels among the supporting actors as a wise older man who once served in the Secret Service. These two figures provide a contrast to the somewhat irritating characterizations of Ellen Benson (Gates) and Peter Benson III (Charney), the former portraying a hysterical woman and the latter an annoying child making illogical statements. However, these stereotypes don’t detract from the film because director Allen maintains the group's dynamic under pressure, creating a claustrophobic atmosphere that builds to an explosive finale. The movie takes place in daylight, and visually it isn’t particularly striking; much of the action occurs within a single living room. The theme of patriotism versus treason is a necessary bit of thematic exposition. Nevertheless, it’s highly recommended as entertainment because this quiet small-town Americana is abruptly shaken out of its complacency. 8/10

Source on TMDB