"I think," said Palk slowly, "there's a homicidal maniac loose in the Hydro, but who it is, God knows. " Presteignton Hydro is a drably genteel spa resort, populated by the aged and crippled who relish every drop of scandal they observe or imagine concerning the younger guests. No one however expects to see gossip turn to murder as their juniors die one by one - no one, that is, except the killer. The crusty cast of characters make solving the case all the harder for Inspector Palk - until the enigmatic sleuth Mr. Winkley arrives to lend a hand. Knock, Murderer, Knock! was Harriet Rutland's sparkling debut mystery novel, first published in 1938. This edition, the first in over seventy years, features a new introduction by crime fiction historian Curtis Evans. 'Very well written, intelligent story of triple murder... acid characterization' Kirkus Reviews