When a bolt of lightning hits a crane on Friday 13th, a bus full of passengers crashes into a shop. We follow the events in the lives of the passengers prior to the accident.

Bus conductor Alf and his driver Fred spend the day at the Derby and Alf expresses his forebodings about working on Friday the 13th. One of the horses they back is a winner, which makes Alf think perhaps the day won't be so bad after all.

Mr Jackson plans to take his wife on a surprise cruise to celebrate their wedding anniversary. He boards the bus after working late, little knowing that his wife has left him that very day for a sleazy fellow named Max.

Cockney market trader Joe is being pursued by a detective, who believes he has stolen a valuable china statue. Two Americans pose as antique dealers from New York City and they travel with him, towards his lockup, on the bus.

Receiving a tip for a stock market certainty, Mr Wakefield asks his wife to hand deliver a letter to his brokers. Afraid to admit to her husband that she has forgotten, Flora Wakefield slips out of the house late at night, and catches the bus towards Wimbledon Common.

Blake is blackmailing a young couple, Frank and Mary, and is travelling on the bus with a cheque for £100 they have given him to keep their secret. Blake knew Frank from a stint in prison and is threatening to tell Frank's employers about his past.

Henpecked husband Ralph meets Dolly in a park. They flirt and kiss. When he takes the bus home he discovers she has stolen his wallet. Smugly, the blackmailer Blake pays his fare for him.

Chorus girl Millie argues with her jealous fiancé, Horace, who insists that she give up her stage career when they marry. When Horace fails to meet Millie at the stage door after work she boards the bus intending to take up a variety agent's offer of supper at his house.

The aftermath of the accident. The bus driver and Alf are in hospital beds. Alf receives attention from a glamorous nurse. Market trader Joe has also survived the crash. He enjoys watching the detective and the two Americans searching through the wreckage of the china shop, which includes the stolen statue he was carrying on the bus. Mrs Wakefield and her stock-investing husband laugh with relief about her forgetfulness, which has saved them from financial ruin. Henpecked Ralph's wife makes a great fuss of him as he has been injured in the crash; they are reconciled. Chorus girl Millie and her beau are happily reunited. She has sprained her ankle in the crash, so cannot dance for a while. Blake's blackmail victims receive a visit from a policeman who informs them that he was killed in the crash, releasing them from worry. The cuckolded Mr Jackson did not survive the accident.

Mrs Twigg and her nephew read about the crash in a newspaper. She observes that they were extremely lucky to have got off the bus just before the crash. The, nephew, however wisely notes that if the bus hadn't stopped to let them off, the crash would never have happened.