The twelve-part serial dealt with secret agents parachuted into occupied Europe during the Second World War, following their progress through initial recruitment and training, and finally their first mission in enemy territory.
The Fourth Arm (Season 1)
Part One (Episode 1)
Writer: John Brason
Air date: 1983-01-07
Runtime: 50 min
Overview: The French Resistance spot a new German weapons base being developed near Calais. Their sabotage attempt goes badly wrong while a Bomber Command mission also proved unsuccessful. SOE decide this needs a trained unit.
Part Two (Episode 2)
Writer: John Brason
Air date: 1983-01-14
Runtime: 50 min
Overview: Returning from France, Gallagher begins to compile a team of specialists to train for a one-off mission behind enemy lines. Not everybody is convinced that some can be trusted to follow orders.
Part Three (Episode 3)
Writer: John Brason
Air date: 1983-01-21
Runtime: 50 min
Overview: Gallagher hands over his new unit to Lt. Col. Squires to begin their training. Scientist Stephen Lovell might be the most vital person on the mission but the army intend to play hardball with him.
Part Four (Episode 4)
Writer: Alfred Shaughnessy
Air date: 1983-01-28
Runtime: 50 min
Overview: Training intensifies with the unit put under extreme interrogation methods to see how they fare. Macaulay's attempted night out becomes a cropper.
Part Five (Episode 5)
Writer: Brian Finch
Air date: 1983-02-04
Runtime: 50 min
Overview: The date of the mission is pushed forward when SOE receives new intelligence that the Germans could have up to 14,000 rockets. Final selection is held before paratroop training begins in earnest.
Part Six (Episode 6)
Writer: Brian Finch
Air date: 1983-02-11
Runtime: 50 min
Overview: Macaulay's position is in doubt when he struggles to overcome his fear on his first parachute. Rohr is informed that she will go into France as reconnaissance before the main group.
Part Seven (Episode 7)
Writer: Gerard Glaister
Air date: 1983-02-18
Runtime: 50 min
Overview: Following a nighttime jump, the unit rendezvous at Pierre de Grouchy's farmhouse. Meanwhile, Gallagher discovers a traitor in the Resistance while former nightclub singer Simone could be recognised.
Part Eight (Episode 8)
Writer: Gerard Glaister
Air date: 1983-02-25
Runtime: 50 min
Overview: After a successful first mission, the unit get debriefed; McKenzie is carpeted for his actions while Gallagher has to inform Simone's mother of her tragic death. Tightrope walker Soltysyk 'Warsaw' is recruited.
Part Nine (Episode 9)
Writer: Michael J. Bird
Air date: 1983-03-04
Runtime: 50 min
Overview: Gallagher wants to be relieved of duty due to attrition rates among the recruits. Lovell starts playing up, causing friction within the group. Meanwhile, Merle and Ferdy start planning a future together if they survive.
Part Ten (Episode 10)
Writer: John Brason
Air date: 1983-03-11
Runtime: 50 min
Overview: The unit has now been reduced to six specialists who will participate in the raid. Lovell is determined to quit but no replacement can be found. His superior Professor Evans is brought in to help change his mind.
Part Eleven (Episode 11)
Writer: John Brason
Air date: 1983-03-18
Runtime: 50 min
Overview: The unit enters France and discover, from Pierre, that the invasion is a mere two days away. The group head to the German rocket base in Deauville. An RAF bomber raid causes the power to go out, allowing the unit to get in.
Part Twelve (Episode 12)
Writer: John Brason
Air date: 1983-03-25
Runtime: 50 min
Overview: The unit have reached the heart of the rocket site. The German kommandant has been made aware that at least three men are on the premises. The group find the documents and plant their bomb but have just sixteen minutes to escape.

Seasons
Episodes 12