The staff contract a strange tropical illness, Marine's Disease, from Mr. Humphries. They are quarantined in the basement until the disease is past.

Captain Peacock's wife works at Grace Brothers, as Mr. Rumbold's secretary. He is intensely jealous and is absolutely convinced that the two of them are having an affair.

Mr. Humphries is made editor of the new staff magazine. The 1st Floor staff is not pleased with the stories he writes about them causing friction in the relations between floors.

The staff go on strike after being threatened with a pay cut or being moved to the bargain basement. They stage a protest on the roof which is interrupted by a fire which destroys the basement.

Old Mr. Grace becomes convinced that Mr. Humphries is his long-lost son. Mrs. Humphries (also played by Mr. Inman) arrives, and shows that she has never had relations with Mr. Grace.

Grace Brothers has decided to enter the video age and display advertisements on closed circuit television throughout the store. Meanwhile, there is a new face in Menswear.

Mrs. Slocombe has dreams in which she and Mr. Humphries become romantically embroiled. When she attempts to turn fantasy into reality, the situation becomes most difficult to handle.

The staff decide to obtain a coat-of-arms for Old Mr. Grace's 90th birthday, but problems arise when they're unable to figure out exactly from where his ancestors came.