In an action by Doctor against Victim to recover $1,000, Doctor's best theory of recovery is that Doctor to go after the promisor in K b/w patient and attorney –First. If Fist had obligation to pay Doctor and failed he is liable to Doctor, secondary to V. In order to invoke liability against First, Doc will assert his rights under creditor- beneficiary of the employment contract between Victim and First. All he need to show that his rights were vested. Indeed, after receiving a bill from Doctor for $1,000, “Victim immediately wrote Doctor explaining that he was unable to pay and enclosing a copy of his contract with First.” As such, Doc can demand from First or Second to whom all duties of K b/w V and First were delegated, including duty to paid creditors.
B/c doctor was creditor –beneficiary not donee, his rights were vested before other creditors (simply first in time.-first in right). Hence, First or Second, broke the K obligation to pay Doctor the fee. First is secondary and Second is primary liable under the assignment (i.e., delegation of duties)