In high school, Jeffrey was known for his talent as a cartoonist, and for his quiet but riotous sense of humor. One of his early cartoons - turned down by magazines such as Playboy, showed a near-empty movie theater and a Dracula-like character pointing to the seat next to a young college co-ed and asking her, "Is this seat taken?" In the summer of 1968, just after finishing his BA at Sacramento State, Jeffrey briefly served as art director for a planned underground newspaper, Parallax, for which he designed the masthead; the paper never appeared. However, his experimental film submission to the UCLA film school, an impressionistic narrative set to "Mac Arthur Park," got him admission to the school, where he did his masters.
Early in his career, he co-wrote the screenplay for Straight Time starring Dustin Hoffman. He then adapted the Stephen King novel The Dead Zone for the screen. In the mid 1980s, Warner Bros. signed him to a long-term contract, resulting in a number of successful films, including The Lost Boys, Innerspace, and the blockbusters Lethal Weapon 2 and Lethal Weapon 3. He also authored the screenplay for Paramount/Lucasfilm's Indiana Jones and the Last Crusade. In 1996, he wrote The Phantom, based on the famed comic book hero and starring Billy Zane and Catherine Zeta-Jones.
He worked on and off on several versions of a third Indiana Jones script for Spielberg, and though several scripts attributed to him have appeared on the web, he confided in his brother, Peter, before his death that none of them were authentic.
One screenplay that Boam was working on near the time of his death was an screen adaptation of author Steve Alten's Meg: A Novel of Deep Terror for Hollywood Pictures.
For television, he wrote and directed an episode of HBO's Tales From the Crypt, and co-created and produced the critically-acclaimed series The Adventures of Brisco County Jr. featuring Bruce Campbell, which premiered on the Fox Network in 1993. Although Brisco ran for only 27 episodes, the series has developed a cult following.
Tragically, his career was cut short when he suffered heart failure as the result of a rare disease which creates accelerated elasticity of muscle tissue, causing the heart and lungs to fail.
