A more thorough explanation:

Definition: Concert of action refers to an action that has been planned, arranged, and agreed upon by parties acting together to further a scheme or cause, making all involved liable for the actions of one another.

Example: A group of friends plan to rob a bank. They agree on the plan and each person has a specific role to play. During the robbery, one of the friends accidentally shoots a security guard. Even though only one person pulled the trigger, all of the friends are liable for the actions of the shooter because they were acting in concert.

Explanation: This example illustrates how a concert of action works. The group of friends planned and agreed to rob the bank together, making them all responsible for each other's actions. Even though only one person committed the violent act, all of the friends are held accountable because they acted in concert.