When birds begin to fall from branches in flocks, it seems someone is using the banned chemical Silent Dust in the countryside of Cornwall. Steed and Peel soon find out a that a small group of local landowners is planning to use the Dust a to blackmail the country by destroying Dorsett.

Dr. Wadkin, one of 7 scientist who have disappeared over the last year, suddenly reappears and attacks his Chinese wife. Steed and Peel find out that all of the missing scientist stayed at room 621 of the Chessman hotel before they vanished. Against her will, Emma poses as a receptionist while Steed pretends to be the famous food critic, M. Gourmet.

A man dressed in tropical clothes is found in Hertfortshire with an Kalayan arrow in his back. He has then fallen into a coma, yet there is no poison to be detected. All clues lead to an delusional Colonel living close by in a simulated tropical climate as if he were still serving in Kalaya. While Emma watches over an increasing number of comatose men, 'Mayor' Steed is invited into the Colonel's officers club with open arms, but is not allowed to leave.