  Chandra LETG+HRC-S and XMM-Newton RGS spectra of H-like C and N formed in the
corona of the lambda And primary star, a mildly metal-poor G8 III-IV first
ascent giant that completed dredge-up ~50 Myr ago, have been used to make a
precise measurement of its surface C/N ratio. We obtain the formal result
[C/N]=0.03+/-0.07, which is typical of old disk giants and in agreement with
standard dredge-up theory for stars of about 1 M_sun or lower. In contrast,
these stars as a group, including lambda And, have 12C/13C ~< 20, which is much
lower than standard model predictions. We show that the abundances of the old
disk giants are consistent with models including thermohaline mixing that
begins at the red giant branch luminosity function "bump". Instead, lambda And
indicates that the 12C/13C anomaly can be present immediately following
dredge-up, contrary to current models of extra mixing on the red giant branch.
