Tom Carmody comes into the home of Thedy and enters her bedroom. She's undressed but clearly comfortable with him being there and they embrace.
Charlie, Thedy's husband and a farmer, is touring the local carnival when he notices a special exhibit: a jar with a strange floating blob of flesh in the center. The carney boss comes over and admits that no one knows what it is, but everyone is fascinated by it. However, he offers to sell it to Charlie for $40, exactly the amount of money that Charlie has on him. The carney boss claims that the thing in the jar told him how much Charlie had. Charlie eagerly buys it, figuring that it'll impress the people in his hometown. As the man puts it in Charlie's truck, he admits that it's been preying on his mind recently and he's tired of seeing it.
Tom admires the bird tattoo on Thedy's arm. She gets him out of her bedroom but tells him to come back later.
On the way home, Charlie stops at the grocery store and offers to show them the jar. Tom Carmody has arrived and says he's got nothing they want to see, but the other townspeople come over. They're intrigued and Charlie invites them to come by his house to look at it. He arrives home and shows the jar to Thedy. She comments that the contents look like him and walks away, uninterested. Charlie talks to the jar, explaining that Thedy takes all of his money and then leaves and claims to visit her folks for weeks at end. Thedy leaves, saying he's already got company and doesn't need him. He watches sadly as she leaves, but then smiles as the townspeople arrive to look at the jar.
The townspeople gather in Charlie's kitchen and look at the jar. Endless intrigued, they speculate about what it might. One man thinks it's a creature from the swamp, another one thinks that it's a kitten that survived drowning. Charlie basks in the reflected admiration.
Thedy parks in a car with Tom and discusses what story she'll tell Charlie. He wonders why she's still with Charlie and she explains that she's free. Tom tells her that the townsfolk were going to see Charlie's jar.
Charlie suggests that the jar thing might be someone they know. A woman thinks it's her dead child, and another man suggests it's an early kind of man. For a second they think it moved but Charlie insists that it's dead. Tom and Thedy come in and Tom insists that it isn't anything but a bunch of old jellyfish. Charlie accuses him of being jealous but Tom puts him down in front of everyone and then leaves with Thedy. She glares at Charlie and then leaves. The townsfolk finally leave and Charlie assures them that they can always come back and look at the jar. Once he's alone, he worries to himself.
Later, Thedy comes in while Charlie is trying to sleep. She tells him that she went with Tom to the carnival and talked to the boss. She laughs and tells him that they found out what is in the jar. The carney boss told them that some hick bought the jar, but all that's inside is dead rat bones, silk, cotton, rubber bands, and pig eyes. Charlie doesn't want to hear, but Thedy insists on telling him. When he realizes she's going to tell everyone, he figures she and Tom have been laughing at him for years. Charlie tells her to do what she wants and then goes and gets the jar. He insists that there is something in the jar besides junk but Thedy assures him that she's telling him the truth. Charlie tells her to come over so he can show her something, and starts calling the cat. Thedy nervously backs away as Charlie advances on her.
The next night, everyone has gathered to look at the jar. They wonder where Thedy is, and Charlie tells them that she went to see her kinfolk for a couple of week. Tom arrives to find Thedy, and Charlie just looks at him and smiles. The townsfolk realize that the thing in the jar looks different, and its hair and eyes are now brown. Tom looks at the jar and notices a bird tattoo on it... just like the one Thedy had. He looks suspiciously at Charlie, who tells him they'll never know what it is.