A wedding turns into a crime scene after the bride falls to her death and everyone including her father is a suspect. Ethan is captivated by Dani but she's already found another love interest.

Susan professes her love for Ian. Gabrielle and Carlos try to rekindle their love. Bree is confronted with Orson's past. In the meantime, Nora and Lynette go to war.

Everyone's lives on Wisteria Lane are forever changed when Carolyn Bigsby holds shoppers hostage at a local supermarket. Meanwhile, Gabrielle and Carlos finish dividing their assets: Gabrielle gets the house, and Carlos gets everything in it. Susan is preparing to go to Paris with Ian.

Lynette returns home from the hospital. Gabrielle decides to get back into modeling and travels to New York. Susan comes home to find Austin and Julie making out on her couch. Bree meets her antagonistic mother-in-law Gloria, with whom Orson is in a quarrel. Detective Ridley has Mike's house searched.

A murdered young woman's body turns up in place of a medical school cadaver during class, leaving Megan to rely on the aid of the star student to help solve the case.

Everyone becomes a suspect when a lottery winner is viciously murdered.

A couple land in the hospital with life-altering injuries after a wrecking ball destroys their home; Lucas and Simone struggle to support a young, terminally ill patient; Richard hosts a prostate screening event.

When a nasty flu season turns out to be masking a terribly infectious disease, Chastain must race to quarantine and diagnose infected patients. While Conrad, Nic and Alec work tirelessly on Meg, who was Nic's favorite guard from her stint in prison, Devon and the others treat Sam, a love-sick patient with flu-like symptoms. Mina finds herself testing Quovadis medical devices in an effort to defend Dr. AJ Austin, who, feeling responsible for the death of a patient, is serving penance by staying away from the OR. Meanwhile, Conrad is prepared to take the next step with Nic, but finds that she may not be as ready.

Conrad, Kit, Mina and the Raptor work to save the life of a med student in need of a triple-organ transplant, drawing Bell back to the OR for one of Chastain's riskiest surgeries yet. After the police find Julian's empty car in a nearby lake, Devon does some investigating of his own to find out what might have happened. Meanwhile, Mina and the Raptor hound Bell to halt his business with the risky medical device company, Quovadis, and Nic makes a rash decision regarding her sister.

When Conrad's attempt to surprise Nic with a lavish Valentine's Day dinner is foiled, he gives the reservation away to someone who could really use it. Mina and Devon distract themselves from all Valentine's celebrations by trying to figure out how their seemingly healthy neighbor has suddenly passed away. Meanwhile, Kit gives dating advice to a sex-injured patient, Irving hits a crossroads in his not-so-secret relationship with Nurse Jessica, and Bell decides to celebrate the day in the OR.