Which agency buys Sterling Cooper in season 3?

McCann Erickson buys Sterling Cooper in season 3 of Mad Men.

The sale occurs because McCann Erickson acquires Putnam, Powell, and Lowe, the British parent company that owns Sterling Cooper. Connie Hilton informs Don Draper that the takeover is coming, leaving the agency’s employees facing an uncertain future inside a much larger advertising network.

Don refuses to accept being absorbed into McCann’s corporate structure. With Roger Sterling and Bert Cooper, he develops a plan to buy Sterling Cooper back. When that attempt fails, the trio uses the contractual consequences of Lane Pryce’s authority to help themselves and key colleagues leave before the sale takes effect.

That escape creates Sterling Cooper Draper Pryce, the new agency formed by Don, Roger, Bert, and Lane. Peggy, Pete, Joan, and Harry are recruited to join. The episode is therefore often remembered less as a simple acquisition than as the event that forces the show’s central agency to reinvent itself.