When Martha and Clark are infected with a toxic virus, it is up to Jonathan to find a cure in time.

What's up with Martha? While digging a hole in the storm cellar to hide the flour canister that holds the octagonal key to the spaceship, Martha is exposed to a green toxic organism. When she returns to the kitchen, she collapses, with Clark catching her before she hits the floor.

At the hospital, Dr. Bryce tells Jonathan she suspects Martha has been exposed to toxins. She's very concerned for her health and that of her unborn baby.

A DCA team (Disease Control Agency) comes to town to trace Martha's last few days. Jonathan reminds Clark to hide the spaceship. Later at the hospital, Martha awakens and tells Jonathan about her secret pregnancy. She believes a surge of energy from the spaceship on the day of the twister healed her, enabling her to get pregnant although doctors said she never could. She also confesses that she hid the octagonal key because she was afraid Clark would want to leave if he discovered his origins.

What's up with Clark? While Clark is in the cellar, he is exposed to the toxins. Pete and Clark take the spaceship in the pickup to hide it in Pete's shed. On the road, Clark weakens, losing control of the pickup, sending it off the road. Clark and Pete struggle to get the truck back on the road, just before the parade of the DCA team passes on the way to the farm. DCA gathers and removes samples from the farm. They find an organic irradiated spore in the cellar where Martha was digging. They also find the flour tin with octagonal key inside and question the Kents who deny knowledge of it.

Later at the farm while Lana visits, Clark passes out. Dr. Bryce rushes to the house, drawing Clark's blood sample. Joanthan refuses to let her take the sample to a lab. He insists she do the blood work herself, and not tell anyone about Clark.

What's up with Lana and Chloe? Because they each care so much, both girls are shook up about the invincible Clark's illness. Lana can't face it. Chloe goes to the farm to visit him. While he is unconscious, Chloe reads Clark a letter she wrote to him, confessing her love. She gets emotional, crying as she touches his face tenderly. Clark murmurs "Lana," sending a hurt Chloe running out of the house. Later at the Torch offices, Lana finds and reads the letter Chloe wrote to Clark.

What's up with Dr. Bryce? Lex comes in just as she finishes examining Clark's blood sample at the hospital. Lex is snooping for info on Martha's condition, but not any getting details from Helen. Dr. Bryce tells Lex she's been offered a 3 year research fellowship at John Hopkins University. He encourages her to take the opportunity.

What's up with Jonathan? Dr. Bryce tells Jonathan Martha will die. Jonathan believes the only hope to save his wife and son are the healing powers of the spaceship. He tells Clark he's going to get the octagonal key from DCA, but Clark should stay behind and rest in his weakened state.

Jonathan sneaks into the guarded DCA warehouse. He finds and takes the key, and is caught by an armed guard. Clark arrives, subduing the guard. Jonathan and Clark make their escape with DCA in pursuit, complete with roadblocks. Somehow they switch trucks with Pete and are able to get to the hospital, while the DCA stops Pete.

Before Jonathan and Clark activate the spaceship in the hospital parking lot, Martha's heart stops. Dr. Bryce and the staff try to revive her, and are about to pronounce her dead. The healing powers of the spaceship's burst of energy fill the hospital, and Martha is revived.

Later Dr. Bryce tells the Kents the unborn baby is healthy, and Martha's recovery is miraculous. She mentions her knowledge of Clark's blood qualities, and asks for an explanation. They cut her inquiry short by agreeing that it must be a miracle.

What's up with Lex? A doctor secretly gives Lex a copy of Martha Kent's medical file. Lex gives Dr. Bryce a key to the mansion, and an invitation to move in. He doesn't want her to lose her opportunity, but at the same time, he wants her to stay so their relationship can grow.

How it ends: Clark has recovered, and attends a benefit party at the Talon. DJ Pete shows Clark his latest CD, "The Talon Mix," as he records the live musical performance on stage.

Clark thanks Chloe for her visit while he was ill. She makes an excuse and walks away quickly. When Clark asks Lana if there's something wrong with Chloe, she tells him they were both worried about him while he was ill. Lana tells him she cares, but is not as good with words as some people. Chloe looks on at the two of them talking, a hurt look in her eyes.