Frank J. Lapidus (Jeff Fahey) is introduced in the second episode of season four as a pilot hired to go on a mission to the island where Oceanic Flight 815 crashed. Frank was introduced with three other main characters from the freighter, Daniel Faraday (Jeremy Davies), Charlotte Lewis (Rebecca Mader) and Miles Straume (Ken Leung), also known as the freighter folk. They were all sent to hunt a captive on the Island, and developed a strong character relationship. In Seasons 5 and 6, Franks develops a close friendship with Jack Shephard (Matthew Fox) as they try to rescue the Oceanic Six, the only passengers to escape the Island.
Frank was supposed to be the pilot of Oceanic Airlines Flight 815, which crashed on an island in the South Pacific. He first appears in Lost while contacting the NTSB to state that the body of the pilot of Flight 815 is not who it is claimed to be, giving viewers the first thought of a cover-up. Frank, who believes there are still survivors, agrees to pilot a plane for Charles Widmore (Alan Dale) who is looking for a fugitive Benjamin Linus (Michael Emerson) an inhabitant of the Island. The helicopter crashes stranding his team of three. Other freighter passengers search for him, and after a disagreement with Martin Keamy (Kevin Durand), the freighter folk are taken prisoner. When a group of survivors overpower Keamy's mercenaries, Frank attempts to fly them to safety, but fails and crashes into the ocean where they are rescued by Desmond's girlfriend Penelope Widmore (Sonya Walger). Penelope takes them home to safety where Frank begins working for Ajira Airways.
Frank encounters the survivors again three years later, while piloting Flight 316 to Guam. His piloting skills were the key to the group being rescued not once, but twice. His ability to work under pressure and to maintain awareness of his surrounding saved the group several times. Frank and the other freighter folk became very popular with their introduction in Season 4 and returned for the last two seasons with more story lines.
"We are not going to Guam, are we?"
"In my experience, people who go out of their way to tell you they're the good guys, are the bad guys."
"Daniel? Couldn't tell ya. Half the stuff he says goes way over my head, the other half goes way, way over."