[3] After being humiliated by members of the Theatre Critics Guild at an awards ceremony, Shakespearean actor Edward Kendal Sheridan Lionheart is seen committing suicide by diving into the Thames from a great height.

Two years later, beginning on the Ides of March, Lionheart sets out to exact vengeance against the critics who failed to acclaim his genius, killing them one by one in ways very similar to murder scenes in the season of William Shakespeare's plays that he last performed.

The fourth critic, Trevor Dickman, has his heart cut out by Shylock in The Merchant of Venice, the play being rewritten so that Antonio is forced to repay his debt with a pound of flesh.

The eighth critic to die, flamboyant gourmand Meredith Merridew, is force-fed pies made from the flesh of his two toy poodles until he chokes to death, replicating the demise of Queen Tamora in Titus Andronicus.

Lionheart's tomb is a Sievier family monument in Kensal Green Cemetery, showing a seated man, one hand placed on the head of a woman kneeling in adoration, while the other holds the Bible, its pages opened to a passage from the Gospel of Luke.

The monument was altered for the film by substituting plaster masks of Price and Rigg for the real faces, replacing the Bible with a volume of Shakespeare, and adding Lionheart's name and dates.

Baldwin was surprised and angered to get a call from Douglas Hickox after he had had a meeting with Browne, telling him that she could have the dresses she requested, increasing the budget solely to accommodate her demands.

[12][13] Similarities with the earlier film include a protagonist who is presumed dead and is seeking revenge; nine intended victims, one of whom works directly with Scotland Yard and survives; themed murders rooted in literature; and a young female sidekick.

The Monthly Film Bulletin wrote: "Although his schematic vengeance invites comparison with that of the Abominable Dr. Phibes, ... Edward Lionheart happily turns out to be a villain of infinitely higher calibre. ...

Douglas Hickox's direction is fairly adroit: he makes effective use of locations, and a constantly moving camera prevents the brazen theatricality of the whole scheme becoming too overt.

The killing of Meredith Merridrew (Robert Morley) by forcing him to eat his pet poodles remains merely unpleasant, though Lionheart has by this time become such a generally sympathetic character that the conventional denouement is both tedious and irritating.

Indeed, Price's superb antics have so effectively upstaged the other performers that the last remaining critic's refusal to alter his original judgment emerges as an act of crass stupidity rather than courage.

Browne recalled in a television documentary Caviar to the General in 1990 that she had not wanted to make "one of those scary Vincent Price movies", but she was persuaded to take the part of Chloe Moon by her friends Robert Morley and Michael Hordern, acknowledging that the film thus had a very strong cast.