The Great Muppet Caper is the second Muppet film and it is considerably more complex than its predecessor, The Muppet Movie, which was essentially just a road movie. As the film begins, Kermit the Frog and Fozzie Bear are reporters who have failed to bag a story of a London jewel heist, which happened under their watch. The real criminals managed to escape and frame Miss Piggy as the thief. Kermit, Fozzie and the Great Gonzo set out on a mission to solve the mystery and track down the criminals who stole the Baseball Diamond. There are fewer star cameos and songs in The Great Muppet Caper than in The Muppet Movie, although appearances from John Cleese and Charles Grodin are particularly memorable.
~ Stephen Thomas Erlewine, All Movie Guide