The Robinsons, a suburban couple, have planned a Mediterranean cruise for themselves and their daughter Joan. On the eve of departure, they are visited by the somewhat uncongenial Wilsons. Joan announces her engagement to Michael Carraway and cries off the cruise. Her brother Peter avoids taking her place; he is entangled with a flashy blonde, Estelle. The disappointed parents decide that their usual trip to Bognor would suit them better, but they keep their change of plan a secret. A fortnight later, Peter and Estelle meet in the empty house, intending to go off for the week-end together. Estelle reveals herself in her true colours and they part company for good. Joan and Michael picnic together; Joan agrees to let him spend that night with her and they go upstairs. Shirley, the maid, comes in, after a quarrel with her young man which she confides to the reformed Peter. Next the parents return, earlier than expected. The indignant Joan accues them of snooping, but Peter's timey appearance saves the situation. Michael has to sleep on the settee, and when Joan creeps down to comfort him, they quarrel and the engagement is broken off. Next day, however, they are reconciled and arrange for a speedy marriage. The Wilsons arrive to ask awkward questions about the cruise.