When undergraduates from Oxford's all-girl Persephone College meet on a cold and dreary January afternoon by the River Cherwell, they are surprised by a canoe floating, apparently empty down the river.

But as it passes close by beneath them they quickly realise that it is not empty and that there is someone lying in it. They pull it ashore only to discover that it is the body of their erstwhile bursar, Miss Myra Denning.

It seems at first as though she had drowned for she was soaking wet but it is soon realised that she would have been unable to get back into the canoe had that been the case...