\documentclass{standalone}

\usepackage{tikz}
\usepackage{shapes}

\begin{document}
\begin{tikzpicture}
  \grid{10}{10}{(0,0)}

  \fill[color=gray](1.5,1.5)--++(5,0)--++(0,3)--++(2,0)--++(0,2)--++(-5,0)--++(0,2)--++(-2,0);

  \fill[color=red](2,1)circle(0.1);
  \fill[color=red](3,1)circle(0.1);
  \fill[color=red](4,1)circle(0.1);
  \fill[color=red](5,1)circle(0.1);
  \fill[color=red](6,1)circle(0.1);
  \fill[color=red](7,2)circle(0.1);
  \fill[color=red](7,3)circle(0.1);
  \fill[color=red](7,4)circle(0.1);
  \fill[color=red](8,4)circle(0.1);
  \fill[color=red](9,5)circle(0.1);
  \fill[color=red](9,6)circle(0.1);
  \fill[color=red](8,7)circle(0.1);
  \fill[color=red](7,7)circle(0.1);
  \fill[color=red](6,7)circle(0.1);
  \fill[color=red](5,7)circle(0.1);
  \fill[color=red](4,7)circle(0.1);
  \fill[color=red](4,8)circle(0.1);
  \fill[color=red](3,9)circle(0.1);
  \fill[color=red](2,9)circle(0.1);
  \fill[color=red](1,8)circle(0.1);
  \fill[color=red](1,7)circle(0.1);
  \fill[color=red](1,6)circle(0.1);
  \fill[color=red](1,5)circle(0.1);
  \fill[color=red](1,4)circle(0.1);
  \fill[color=red](1,3)circle(0.1);
  \fill[color=red](1,2)circle(0.1);

\draw[color=red, dotted, line width=2pt](2,1)--(3,1)--(4,1)--(5,1)--(6,1)--(7,2)--(7,3)--(7,4)--(8,4)--(9,5)--(9,6)--(8,7)--(7,7)--(6,7)--(5,7)--(4,7)--(4,8)--(3,9)--(2,9)--(1,8)--(1,7)--(1,6)--(1,5)--(1,4)--(1,3)--(1,2)--cycle;

\end{tikzpicture}
\end{document}

