A few minutes before her wedding to Derek Dietl (Paul Rudd), a TV weatherman, Susan Murphy (Reese Witherspoon) is hit by a meteorite. The meteorite is infused with quantonium, a rare and powerful element that causes her to grow -- just as she begins to recite her vows -- to an enormous size. Targeted by the government as a monster, Susan is captured and imprisoned at a secret facility where other such oddities are being held, including Dr. Cockroach (Hugh Laurie), a mad scientist who accidentally transformed himself into a roach-human hybrid; B.O.B. (Seth Rogen), a gelatinous, brainless, but talkative mass brought to life in an experiment gone wrong; the Missing Link (Will Arnett), a Creature-from-the-Black-Lagoon-like lizard man; and the skyscraper-sized mutant larva Insectosaurus. Their jailer is General W.R. Monger (Kiefer Sutherland).