YA spy revenge book, possibly based off tv

[Catherine]

5 people all end up on an island, and are forced to climb a mountain. 3 girls and 2 boys are trained to be spies with combat and survival skills. They find out about each other through files, and how they are all connected. Each person has a grudge and wants to get revenge on somebody else. They go on a mission, where something goes wrong and a guy gets killed. They go back to the island for more training.

This book was read about 2 years ago, and might be based off a tv or movie series. This may be the first book of a series.

Thank you!

[Kris]

A guess - The Unwanteds by Lisa McMann?

[Lobstergirl, au gratin]

Catherine, are you still looking for this or did you find it?