Monkey Business: GTA 5 Mission Walkthrough

Monkey Business is a break in at a research facility. The crew needs a nerve toxin from inside, and the way in is underwater.

Walkthrough

Drive the dinghy to the facility, dive in and swim to the underwater tunnel.
Use the underwater cutter on each burn point to open the steel cage. Only fire it at the burn points to save fuel.
Swim through the long tunnel to the lab, surface and climb the ladder.
Michael now carries a stun gun. Stun the staff as you move through the halls, take a key card from the worker in the elevator and ride up.
At the security doors, wait for the two guards to come out and stun them.
The scientist with the toxin locks himself in. Once he opens up, stun him and grab the toxin.
The alarm sounds. Switch to a short range weapon and fight your way to the loading docks, then put the toxin in the refrigerated unit.
As Trevor, lift the container with the helicopter and fly it to the Sandy Shores airfield. Drop it on the flatbed and land.
Finish with a short drive as Trevor after the cutscene.

Count your stuns. You need at least eight, and using Michael’s special ability at the security doors lets you get both guards before the others shoot one.
IGN suggests a fully upgraded pump shotgun for accuracy and a rifle for speed. You may need a replay to get both.
The facility has armored gunmen at the edge of your view. Stay in cover and pick them off one at a time.

Updated October 27, 2026