diff --git a/Cargo.lock b/Cargo.lock
index e2fd3cf..ac975d8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -79,6 +79,12 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "fixedbitset"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37ab347416e802de484e4d03c7316c48f1ecb56574dfd4a46a80f173ce1de04d"
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -227,6 +233,7 @@ name = "gh-stack"
 version = "0.1.0"
 dependencies = [
  "futures",
+ "petgraph",
  "reqwest",
  "serde",
  "tokio",
@@ -575,6 +582,16 @@ version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d4fd5641d01c8f18a23da7b6fe29298ff4b55afcccdf78973b24cf3175fee32e"
 
+[[package]]
+name = "petgraph"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "467d164a6de56270bd7c4d070df81d07beace25012d5103ced4e9ff08d6afdb7"
+dependencies = [
+ "fixedbitset",
+ "indexmap",
+]
+
 [[package]]
 name = "pin-project"
 version = "0.4.17"
diff --git a/Cargo.toml b/Cargo.toml
index e15f57b..9aa086e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,3 +11,4 @@ reqwest = { version = "0.10.6", features = ["json"] }
 tokio = { version = "0.2", features = ["full"] }
 serde = { version = "1.0", features = ["derive"] }
 futures = "0.3.5"
+petgraph = "0.5"
diff --git a/src/api/search.rs b/src/api/search.rs
index 4830baa..c57c7da 100644
--- a/src/api/search.rs
+++ b/src/api/search.rs
@@ -2,26 +2,28 @@ use futures::future::join_all;
 use serde::Deserialize;
 use std::error::Error;
 
-use crate::{api, Credentials};
+use crate::{api, markdown, Credentials};
 
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 pub struct SearchItem {
     url: String,
     title: String,
 }
 
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 pub struct PullRequestRef {
     label: String,
     r#ref: String,
     sha: String,
 }
 
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 pub struct PullRequest {
     id: usize,
+    number: usize,
     head: PullRequestRef,
     base: PullRequestRef,
+    merges_into: Option<Box<PullRequest>>,
     title: String,
 }
 
@@ -33,8 +35,22 @@ impl PullRequest {
     pub fn base(&self) -> &str {
         &self.base.label
     }
+
+    pub fn set_merges_into(&mut self, into: PullRequest) {
+        // `clone` here to avoid an explosion of lifetime specifiers
+        self.merges_into = Some(Box::new(into))
+    }
 }
 
+// impl markdown::AsMarkdown for PullRequest {
+//     fn as_markdown_table_row(&self) -> String {
+//         match self.merges_into {
+//             Some(into) => format!("|#{}|{}|#{}|", self.number, self.title, into.number),
+//             None => format!("|#{}|{}|`develop`/feature branch|", self.number, self.title),
+//         }
+//     }
+// }
+
 #[derive(Deserialize, Debug)]
 struct SearchResponse {
     items: Vec<SearchItem>,
diff --git a/src/graph.rs b/src/graph.rs
index e871e40..bcb6777 100644
--- a/src/graph.rs
+++ b/src/graph.rs
@@ -1,34 +1,23 @@
 use std::collections::{HashMap, HashSet};
+use petgraph::visit::IntoNodeReferences; 
+use std::rc::Rc;
+use std::cell::RefCell;
+use petgraph::Graph;
 
 use crate::api::search::PullRequest;
 
-pub fn build(prs: &[PullRequest]) {
-    let mut heads = HashSet::new();
-    let mut prs_by_base = HashMap::new();
+pub fn build(prs: Vec<Rc<PullRequest>>) -> Graph<Rc<PullRequest>, usize> {
+    let mut tree = Graph::<Rc<PullRequest>, usize>::new();
+    let heads = prs.iter().map(|pr| pr.head());
+    let handles: Vec<_> = prs.iter().map(|pr| tree.add_node(pr.clone())).collect();
+    let handles_by_head: HashMap<_, _> = heads.zip(handles.iter()).collect();
 
-    for pr in prs.iter() {
-        heads.insert(pr.head());
-        let entry = prs_by_base.entry(pr.base()).or_insert(Vec::new());
-        entry.push(pr);
-    }
-
-    let roots: Vec<&PullRequest> = prs.iter().filter(|pr| !heads.contains(pr.base())).collect();
-    let results = resolve(&roots, &prs_by_base);
-}
-
-fn resolve<'a>(
-    roots: &Vec<&'a PullRequest>,
-    prs_by_base: &'a HashMap<&str, Vec<&PullRequest>>
-) -> Vec<&'a PullRequest> {
-    let mut results = Vec::new();
-
-    for &root in roots.iter() {
-        results.push(root);
-        if let Some(children) = prs_by_base.get(root.head()) {
-            let mut children = resolve(children, prs_by_base);
-            results.append(&mut children);
+    for (i, pr) in prs.iter().enumerate() {
+        let head_handle = handles[i];
+        if let Some(&base_handle) = handles_by_head.get(pr.base()) {
+            tree.add_edge(head_handle, *base_handle, 1);
         }
     }
-    
-    results
+
+    tree
 }
diff --git a/src/lib.rs b/src/lib.rs
index 841d60f..acb7cc6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,6 @@
 pub mod api;
 pub mod graph;
+pub mod markdown;
 
 pub struct Credentials {
     // Personal access token
diff --git a/src/main.rs b/src/main.rs
index 7d2dd50..9b17b5f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,10 +1,12 @@
 use std::collections::HashMap;
+use std::rc::Rc;
 use std::env;
 use std::error::Error;
 use std::process;
 
 use gh_stack::api;
 use gh_stack::graph;
+use gh_stack::markdown;
 use gh_stack::Credentials;
 
 #[tokio::main]
@@ -25,7 +27,11 @@ async fn main() -> Result<(), Box<dyn Error>> {
     let credentials = Credentials::new(token);
 
     let prs = api::search::fetch_pull_requests_matching(&pattern, &credentials).await?;
-    graph::build(&prs);
+    let prs = prs.into_iter().map(|pr| Rc::new(pr)).collect();
+    let tree = graph::build(prs);
+    println!("{:?}", tree);
+
+    // markdown::build_table(&graph[..]);
 
     Ok(())
     /*
diff --git a/src/markdown.rs b/src/markdown.rs
new file mode 100644
index 0000000..d6b16c1
--- /dev/null
+++ b/src/markdown.rs
@@ -0,0 +1,8 @@
+use crate::api::search::PullRequest;
+use std::fmt::Display;
+
+pub trait AsMarkdown {
+    fn as_markdown_table_row(&self) -> String;
+}
+
+pub fn build_table<T: Display>(graph: &[T]) {}