This section contains a summary of Babylon 5's story arc (the 5-year plotline) up to, but not including, "Whatever Happened to Mr. Garibaldi?." Note that this is chock full of spoilers!
G'Kar set out in search of Garibaldi, who was taken by a Shadow ship during Sheridan's confrontation with the Shadows, in "The Hour of the Wolf." Londo took up a position in the royal court, but soon discovered that the Emperor was insane and had made a deal with the Shadows in the belief that they would elevate him to godhood. A rescue mission was mounted to Z'ha'dum, but Sheridan was nowhere to be found. Somehow, though, he survived, and found himself at the bottom of the chasm accompanied by an enigmatic alien.