For those who liked Hubble's Bubble (1964) this is more of the same, as the Boffins' Club goes on to try experiments three and six in Alaric's book of magic spells. The Hubbles by the way are Alaric and Sarah, and their Grandfather and Charlotte, Jonathan, and Peter Vaughan make up the rest of the Boffins' Club. A clue to treasure buried during the English Civil War gives them the idea of trying the third experiment, which allows travel back into time. The other experiment, which makes it possible to breathe under water, is used when a prehistoric hippopotamus, fetched back from a miscalculated trip into history, is lost. The transition to fantasy is always smoothly made, although the course of events often seems illogical or incidental. The Boffins' members keep up a steady banter often pleasantly silly, frequently affected, and always very British.