Not terrible, but pretty close. It's difficult to not be disappointed in a movie that features Jason Robards, Herbert Lom AND Michael Dunn and still manages to be dull. Robards leads an theatre troupe whose members are being killed after being splashed with acid. Detective Adolfo Celi suspects Lom (who "died" years earlier). Aside from the presence of various men in gorilla costumes, the movie bears little resembles to Poe's story. Nevertheless it's well directed by Gordon Hessler with a lot of period detail (and Spain makes a nice substitute for France). Robards is just OK, Lom is fairly creepy and Dunn is exploited as a sinister dwarf. Christine Kaufmann (a actress of little talent and even less presence) plays Robards nubile young wife, plagued by nightmares and premonitions of things to come. Lili Palmer appears briefly as Kaufmann's mother.
Review of Murders in the Rue Morgue
