This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
Ordinarily the only remedy in a case of contract or conveyance made by undue influence is a rescission, either informally at law, or formally in equity. An action for damages will not lie.1 If, however, the person who has received property by means of undue influence exerted by him upon the adversary party has transferred it to a purchaser in good faith without notice, the person subjected to such undue influence may recover the value thereof from the original wrong-doer.2 If the party guilty of undue influence retains the property received by such means he must account for the reasonable value thereof. Thus in case of a sale of a legacy induced by undue influence, it has been held that the vendor may recover the difference between the actual value of the legacy and what he received for it under such contract.3