We report the detection of the Pb I 4057.8Å line in the very metal-poor ( [ Fe/H ] = -2.7 ) , carbon-rich star , LP 625-44 .
We determine the abundance of Pb ( [ Pb/Fe ] = 2.65 ) and 15 other neutron-capture elements .
The abundance pattern between Ba and Pb agrees well with a scaled solar system s -process component , while the lighter elements ( Sr-Zr ) are less abundant than Ba .
The enhancement of s -process elements is interpreted as a result of mass transfer in a binary system from a previous AGB companion , an interpretation strongly supported by radial velocity variations of this system .

The detection of Pb makes it possible , for the first time , to compare model predictions of s -process nucleosynthesis in AGB stars with observations of elements between Sr and Pb .
The Pb abundance is significantly lower than the prediction of recent models ( e.g. , 5 ) , which succeeded in explaining the metallicity dependence of the abundance ratios of light s -elements ( Sr-Zr ) to heavy ones ( Ba-Dy ) found in previously observed s -process-enhanced stars .
This suggests that one should either ( a ) reconsider the underlying assumptions concerning the ^ { 13 } C-rich s -processing site ( ^ { 13 } C-pocket ) in the present models , or ( b ) investigate alternative sites of s -process nucleosynthesis in very metal-poor AGB stars .