Based on a 1981 off-Broadway play written by Kevin Wade, Key Exchange is a crisp comedy of manners about young urban professionals who, while quite capable at work, find themselves less apt when it comes to relationships.
Philip (Ben Masters), a writer, has an "open relationship" with Lisa (Brook Adams), an associate producer of a New York TV talk show. Although he is happy with a no-strings-attached arrangement, she wants something more. Philip reluctantly agrees to exchange apartment keys. Meanwhile, his new friend Michael (Daniel Stern), a Central Park bike rider like himself, is upset because his wife has left him for a fling after a few days of marriage.
The pressures of sexual politics are put on the back burners as these hard working individuals struggle to get ahead. Philip researches a mystery novel by accompanying a detective (Danny Aiello) on a stakeout. Lisa devotes herself to making talk show host David Slattery (Tony Roberts) happy in his hectic job which involves interviewing infertile couples and mercy killers. And Michael, a lawyer, does pro bono casework, including coaching a Spanish immigrant for citizenship.
At one point, Philip tells Michael, "I want to have my cake and have my cupcake too." Lisa realizes that he is unequal to the challenge of a more in-depth relationship. She decides to leave him to pursue a job opportunity in Los Angeles. This decision gives Philip a final opportunity to clarify his values to see whether cupcakes are that important after all.