Landry calls for a get-together to unwind at Jack's cabin in the woods and Mitchell arrives…but everyone else can't make it yet. They go into the cabin but are unaware that someone is watching them from the woods. While Sam is in charge of SGC, Teal'c is assisting SG-3 and Colonel Reynolds on P9J-333 where some animal is savaging the local villagers.
They meet back at SGC and Sam sends Vala and Teal'c back, suspecting Ori involvement, then lets Landry know they're going to be delayed. Mitchell is uncomfortable "cutting loose" with his superior.
On 333, Teal'c leads SG-3 when the other team, SG-25, is under attack and signals for help. They find a few survivors but the others are dead.
That night as a storm comes in, Landry tells Mitchell that he needs Mitchell to keep on holding SG-1 together.
Vala returns to the Stargate when she hears some creature, but Teal'c arrives first. He doesn't hear anything but then the creature comes out of the woods and Teal'c kills it with a grenade.
Later on Earth, Mitchell wakes up and finds Landry missing. Grabbing a gun, he goes to find the General only for Landry to find him with a shotgun. They narrowly avoid shooting each other. The next morning Mitchell prepares to head out but Landry announces the storm washed out the road back to town, and it's the only road.
Back on Earth, Vala chats with Sam and sits in Landry's chair, and Sam lets her know that Landry and Mitchell are unavailable. Landry wants to take Mitchell out bird watching but Mitchell declines and goes out jogging, as something still watches in secret from the woods.
Dr. Redden is doing an examination of the dead animal when a slug-like creature crawls out of it stomach and only quick action by Teal'c stops it.
Mitchell finds a hunter in the woods who calls him over for assistance – two hunters have been brutally savaged by what they claim is a bear.
Dr. Redden determines that the slug lodged itself in the stomach of a local herbivore and mutated it into a savage killer. The locals haven't heard of such a creature, and everyone wonders how the slug got there.
Landry talks to the local sheriff and suggests he seal off the area and kill the bear, but it's hunting season and he's understaffed, so there's not much he can do.
A team returns from another planet, having been attacked by the same type of mutated creature. No one has heard of them but they're only showing up on worlds that SGC teams have visited.
Landry and Mitchell go out to hunt the creature and Mitchell goes off after a noise as Landry gets a report that the sheriff has discovered another body. Landry goes off after Mitchell and finds him with some hunters and yet another dead body.
Sam goes over the mission logs and determines that both teams used Sodan cloaking devices to remain hidden on the planets they visited. Sam reveals that one of the cloaking devices is missing from Area 51. They check out the cloaking devices they have and they all show up as okay. However, the next device Teal'c tries generates a heightened radiation field and Teal'c sees a slug. He cuts off the cloak and the creature is revealed, but it is moving slowly.
Landry and Mitchell are in the woods when they hear more gunshots. Mitchell investigates and spots blood, and traces it to a cloaked man who reappears.
A medical exam determines that Teal'c is healthy, and Sam speculates that the cloaking device puts the person in a subspace pocket and the creatures are bleeding through into reality, but they don't affect the person in the field.
Mitchell interrogates the man and figures he's with the Trust and spying on Landry and Mitchell. The man is unaware that the Goa'uld are running the Trust. Landry contacts Sam, who explains that the creatures are repelled by the unshielded devices, but SGC put in a shield to cut off the radiation which repelled the creatures. Sam figures that the creature in the woods is another mutated bear and far more dangerous.
Mitchell and Landry cover up the Trust man's involvement although the sheriff isn't too happy. Landry takes over the hunt but the mutated creature leaps out of the woods and hauls the sheriff away in a matter of seconds.
Landry calls in the SGC teams who seal off the area with packages of the radiation then prepare to hunt down the mutant. The SGC teams move through the woods and close in on the creature. It attacks them and they open fire, driving it off. It comes back for more and they manage to bring it down with concentrated firepower. Another creature comes out of the woods and Sam and Teal'c gun it down.
Later at the cabin, SG-1 enjoys a relaxing game of poker as Landry announces they've checked the area and it appears to be clear, but are sealing off the perimeter with radioactive beacons just in case. Sam wins a game of poker and Mitchell admits he's actually getting to relax.