The gas canister is super important for the Toxic Relationship quest in Dying Light: The Beast. In this guide, you will find details on finding the canister with Survivor Sense, retrieving the canister from its hideaway, and putting it into the gas holder correctly so that you will be set for the encounter with the Chimera.
Tracking the Gas Holder Device

Having to find the gas canister for the gas holder that will come in handy in dealing with Chimera is your first task in the Toxic Relationship quest in Dying Light: The Beast. The gas holder device is situated in a stone hedge in National Park just off the forest and might either be walked or driven to from the edge of town.
Retrieving and Installing the Gas Canister

Using your Survivor Sense, the canister can be spotted easily. It is hiding in a bush on the left side of the park and can be picked up by interacting with it. Afterward, you need to set up the gas holder with the canister.
Once the objective has been completed, it will lure the Chimera, but for now, the primary focus is not just on finding the canister and setting it in the correct place but also on equipping yourself for the greater challenges that await you ahead. Strong melee weapons and other supplies should help with this preparation.