The auditions begin with creator and executive producer Simon Cowell at the judges table alongside Heidi Klum, Mel B, Howie Mandel, and host, Nick Cannon. The Golden Buzzer is back and allows four lucky acts the chance to go directly to the live performance rounds at the Dolby Theatre in Los Angeles to compete for America's vote.

The world is turned upside down by the seemingly impossible and horrifying murder of Retro Girl. Pressure is on the Powers Division to bring the perpetrator to justice, but when Christian Walker is pulled off the case for being too close to the victim, and may be a suspect himself, he must go off-the-books to avenge the woman he loved.

Lex clashes with Capt. Scott; the data recovery center comes under attack; a desperate plea from Jana leaves Lex's world in chaos.

Redcoats attempt to persuade slaves to run away and join the English army; Kunta escapes but slave catchers apprehend him and amputate half of his foot to ensure he never runs off again; John Waller sells Kunta to his younger brother, William.

During the final throes of the season's first arctic storm, the captains and crews need to battle for survival. While other captains fight the weather, rookie skipper Sean Dwyer decides to wait out the storm, making his first trip of the year under blue skies.

Ramsay helps the married owners of a Southbridge, Mass., inn modeled after a historic Austrian bed and breakfast update their business.

On the day of Retro Girl's funeral, Detectives Walker and Pilgrim prepare to combat violence between rival gangs The Quantums and The Hacks. Hoping to fill her place, Calista makes her public debut as New Retro Girl. Still reeling from Retro Girl's death, and with her murder officially closed, Walker doggedly pursues a suspect he believes to be the real murderer.

Finch's number comes up when a fatal error blows his cover identity and sets off a deadly series of escalating encounters with Samaritan's operatives.

Commander Cross unofficially reopens the Retro Girl case, ordering Pilgrim and Walker to lead a covert investigation that may put them in a life-threating situation. Meanwhile, Los Angeles goes in lockdown mode as gang warfare reaches a fever pitch, pulling the revered Power, SuperShock out of retirement.

Danny's old partner in crime in Miami is determined to make the Rayburns pay. Investor Roy Gilbert agrees to fund John's campaign, on one condition.

Mindy takes a spontaneous trip to visit Peter in Texas, where she tries to seduce a handsome stranger. Meanwhile, Peter is keeping a secret from his wife, Lauren.

Today's off-site challenge will take place at George Calombaris' Hellenic Republic restaurant. Split into two teams, each team must prepare a three course feast for 120 guests to avoid elimination.