Complex sentence: But during his presentation of the process to U.N.C.L.E. he dies from apparently natural causes (though we later discover is due to Randolph's doing), and his dying words are that his daughter is the key to finding the formula.
Split into simpler sentences: But during his presentation of the process to U.N.C.L.E., he dies from apparently natural causes (though we later discover is due to Randolph's doing). True's dying words are that his daughter is the key to finding the formula.