[@Guardian Angel Haruki]
Assuming the Bandit Leader has the same speed as Mirdas, and since he didn't dash, Mirdas will use his movement to chase the Bandit Leader before using his Attack Action to grapple the Bandit Leader. Mirdas's Athletics roll to make the grapple is a [url=https://www.roleplayerguild.com/rolls/4944]15.[/url] From what I know with grappling rules, and without knowing the Bandit Leader's capabilities, the Bandit Leader will have to beat it with either an Athletics or Acrobatics check. 

It's wrassling time.