From the publisher:
Time to Bring in the Experts
Yes, GURPS Action is back with a vengeance!
Action heroes might be stereotyped, but they rarely fit into nice, neat boxes. Studios spend big bucks making sure we all know exactly what's special about the hero of their latest blockbuster. While Action 1: Heroes and Action 3: Furious Fists are up to the challenge of creating characters who stand out, there are times when 250-point templates aren't quite the right tool for the job.
That's when you call in Action 4: Specialists. Its modular design system lets you pick and choose from over 100 areas of expertise to create exactly the right hero for the mission, while its systematic advice on filing off rough edges and filling in holes gives you a lean, mean action machine.
But that's not all!
This system is also useful for:
Running Action at lower- and higher-than-usual power levels, from 125 points on up.
"Leveling-up" characters, no matter how they were designed.
Quickly designing NPCs, be they Allies, generic supporting cast, or bad guys.
Because when the going gets tough, you send in the professionals!