Showing Wycliffe and the Guild of Nine by W. J. Burley

The artist's colony is at the site of a disused mine working on the moor west of St Ives, and it's run by Archer and his wife Lina, according to astrological principles. The newest member of the colony is Francine, a beautiful if fey young woman with a legacy to invest. Archer isn't keen - not least because she is a Scorpio - but Lina takes a more pragmatic view.

Then Francine is found dead, killed by a deliberately blocked gas-heater flue.

Wycliffe investigates - and soon discovers that several members of the colony have very good reasons for not wanting the police poking into their affairs . . .