Bellamy and Monty meet with Kane and Indra so they can head out in search of Clarke in episode #301 "Wanheda, Part 1".
From episode #111 "Fruit of a Poisonous Tree".
Amaya, Rory, and Nate head to where the battle between the army and the Dominators is occurring to capture a specimen only to be captured by government agents in episode #207 "Invasion!".
Source: Vancity Buzz