George Gadberry, an out-of-work actor whose chief claim to fame was a leading role in "The Rubbish Dump" is down to his last intact florin, and has to vacate his current lodgings unseen as he cannot pay his landlady the previous week's rent. Not only is he broke, but the Tax Inspector is beating at the door. Then his agent calls with a mysterious commission, and George meets a man who, once he removes his false beard, could be his identical twin.
As you may have already guessed from this book's title, George lets himself be persuaded into a major impersonation. Nicholas Comberford wants to return to the Riveria and fall back into the arms of his mistress, while George travels up to Bruton Abbey on the chilly Yorkshire dales and pretends to be him. Nicholas cheerfully admits to being a rogue and a sensualist, but he wants to secure a place in the will of his fabulously wealthy Great-Aunt Prudence. Unfortunately, his great-aunt is a strict teetotaler. Fortunately, she has a weak heart and isn't expected to last out the year.
George travels up to Bruton Abbey under the guise of the reformed prodigal coming home to comfort Great-Aunt Prudence in her precipitous decline toward the family burial vault. Nicholas has loaned him the memoirs of Great-Uncle Magnus to bone up on family history, and at first no one seems to suspect the changeling in their midst.
But George realizes that Nicholas has misled him on two minor items: Great-Aunt Prudence has no objection to alcohol; and the old woman is in ruddy good healthy and is expected to live for decades.
Then Miss Bostock, Great-Aunt Prudence's companion begins to blackmail George as the imposter that he is. Can anything else go wrong?
Well, yes. Great-Aunt Prudence attempts to fix her false heir's interest in one of the neighboring landowner's hearty twin daughters. Her butler attempts to play Miss Bostock's blackmailing game with George. Bats and owls flit nightly through the vast halls of the abbey, and a gigantic man-eating carp lurks beneath the ice of the ornamental pond. The local rector, who seemed to be settling into a malignant version of senile dementia, is revealed as a practitioner of the Black Arts. And then, to cap off all of his misfortunes, George falls in love.
Michael Innes has produced another amusing, but sharply-edged comedy-of-manners that had me laughing out loud when I wasn't commiserating with poor George. He seemed like a very decent sort of penurious actor whose brush with the Tax Inspector and then the rogue, Nicholas led him disastrously, almost fatally astray. I had to keep reading to find out if Innes's likeable, although somewhat weak-willed hero would wriggle out of Great-Aunt Prudence's matrimonial schemes, the blackmailing clutches of her staff, the lurking jaws of the carp, and last but not least, the dilemma of his false inheritance.