  We present a high-resolution study of a massive dense core JCMT 18354-0649S
with the Submillimeter Array. The core is mapped with continuum emission at 1.3
mm, and molecular lines including CH$_{3}$OH ($5_{23}$-$4_{13}$) and HCN (3-2).
The dust core detected in the compact configuration has a mass of $47
M_{\odot}$ and a diameter of $2\arcsec$ (0.06 pc), which is further resolved
into three condensations with a total mass of $42 M_{\odot}$ under higher
spatial resolution. The HCN (3-2) line exhibits asymmetric profile consistent
with infall signature. The infall rate is estimated to be $2.0\times10^{-3}
M_{\odot}\cdot$yr$^{-1}$. The high velocity HCN (3-2) line wings present an
outflow with three lobes. Their total mass is $12 M_{\odot}$ and total momentum
is $121 M_{\odot}\cdot$km s$^{-1}$, respectively. Analysis shows that the
N-bearing molecules especially HCN can trace both inflow and outflow.
