Magnum is hired to protect a British Brigadier who is hunted by the IRA.
Magnum returns from a case to find that Higgins' old Army commander is staying on the Masters' estate, under tight security, until some I.R.A. members he helped capture are tried. Two secret intelligence agents hire Magnum to protect the brigadier and foil assassins out to kill him before the terrorists' trial, but the "need to know" basis the Agents insist on operating by only serves to complicate matters for Magnum.
- Tom Selleck as Thomas Sullivan Magnum IV
- John Hillerman as Jonathan Quayle Higgins III
- Roger E. Mosley as Theodore "T.C." Calvin
- Larry Manetti as Rick Wright
- Robin Dearden as Mandy, the Flight Attendant
- Edward Grover as Hooker, the CIA Agent (credited as Ed Grover)
- Richard Johnson as Brigadier General Alistair Ffolkes, Royal Army
- Mariko Van Kampen as Suzie, the Flight Attendant
- Remi Abellira as Mok
- Reri Tava Jobe as Hostess (credited as Reri Tava)
- Gene Hamilton as CIA Agent Dobey (credited as Eugene Hamilton)
- David O'Malley as Dirk (credited as David P. O'Malley)