It's pay day at Grace Brothers and the staff realize that their money just doesn't go very far. An opportunity for a bonus arises when a customer loses a diamond and offers a £100 reward. Greed gets the better of everyone, except Mr. Grainger, and soon they're conspiring behind each others backs. Mr. Mash throws a wrench in the search after he damages a jeweled dress, causing a multitude of "diamonds" within the department.

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

Bad news. Grace Brothers may be bought by the Japanese. The staff take their problems to Number Ten, where they speak with President Reagan by phone. Mrs. Thatcher gets fashion tips from Mr. Humphries.

When Mrs. Slocombe's cat turns up missing, she decides that only Mr. Humphries could take its place.

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.

Security cameras are again installed at Grace Brothers, and when the staff bet their bonuses on a horse race, it's up to Mr. Humphries to mime the race to them by closed-circuit.

The staff prepare for a visit by the Queen. The visit is abruptly ended when Mrs. Slocombe accidentally pushes a flower pot out the window, nearly hitting the Royal Couple.

Mr. Humphries is accused of stealing and his distinguished career could end in disgrace. In a trial, he is found guilty and dismissed, but Mr. Harman finds the missing money in the back of the till from which it was supposedly stolen.

This episode we find Mr. Spooner is about to be discovered by a record company. One problem is that his voice keeps giving out. Mr. Humphries gives him a tonic and he recoveres for a little while. While auditioning on tv with Grace Brothers Staff, his voice gives out.

Mr. Goldberg runs an agency to get the staff better jobs. After Captain Peacock and Mr. Rumbold become aware of this, Mr. Humphries and Mrs. Slocombe are given raises, and decide to stay with the store.

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.

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.

When the handsome golf pro from Sports comes to the floor for a demonstration, he accidentally hits Mrs. Slocombe. She then thinks she's a little girl, wrecking havoc on the store as she cavorts around the department.

When traveling to and from work becomes difficult, the staff threaten to resign unless they receive a travel allowance. Old Mr. Grace offers them the empty apartments on the top floor as living space, but they soon discover cohabitation isn't what it's cracked up to be.

To celebrate Mr. Grace's 80th birthday, the staff organize This is Your Department, a spoof of This is Your Life.

Captain Peacock is challenged to a boxing match by a member of another department. He backs out, and Mr. "Hugger" Humphries is "elected" to take his place in a wrestling match. He loses that match, but Mrs. Slocombe enters the ring and defeats the challenger.

Mrs. Slocombe sells her home-made perfume. After a misunderstanding, Mrs. Peacock finds Captain Peacock without his pants (perfume had spilled on them) and the ill-fated trousers in the hands of Mr. Rumbold's secretary.

The staff perform a play on CB radio to advertise Grace Brothers. The play results in the store being swamped by truck drivers who are driven off by Mr. Humphries and Mrs. Slocombe.

When the store is robbed late one night, the staff determine to capture the burglars themselves.

An after-hours staff meeting produces an idea to introduce background music and a recorded voice; the only question is--whose voice?

Sales figures are down; profits are low. Young Mr. Grace is forced to make some economies. The threat of redundancies is looming. Someone is going to have to go - but who is it to be?

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.

It is Young Mr. Grace's birthday and there is the traditional free lunch for staff in the canteen. Afterwards, the staff plan a much more festive event for the celebration.