Starring Dennis Quaid as Lt. Tuck Pendleton, Martin Short as Jack Putter, and Meg Ryan as Lydia Maxwell, InnerSpace was released in 1987. The movie was inspired by a 1967 flick called Fantastic Voyage. The movie was part science fiction, part comedy, and part romance. It received good reviews, did well at the theatre, and even scored a couple of Academy Awards and an Oscar.
In the movie, Tuck volunteers for a top-secret miniaturization experiment. The plan is to shrink Tuck, along with a spaceship, and inject him into a rabbit. After the shrinking, the lab is attacked by a rival scientist, whose intention is to steal the technology. In the fracas that ensued, Tuck is injected into the body of Jack Putter, a grocery store clerk who happened to be in the wrong place at the wrong time. Tuck quickly realizes he is not in a rabbit, but instead in a human. He makes contact with Jack and explains that he must get back to the lab in a timely manner due to the oxygen levels on his ship.
During the raid on the lab, a critical piece of technology, required to de-miniaturize Tuck, was stolen. Tuck and Jack enlist the help of Tuck's girlfriend, Lydia, to hatch a plan to get the needed technology back from the criminals. The plan is foiled, and Jack, Tuck, and Lydia are captured. During their imprisonment, Jack and Lydia share a kiss, and Tuck is transferred into Lydia's body. The group is able to get the equipment, partially miniaturize the bad guys, and eventually get Tuck back to normal size, just before time ran out. The movie ends with Tuck and Lydia getting married, and Jack running after them after he finds out the half-miniaturized baddies are stowaways.