diff --git a/Cargo.lock b/Cargo.lock
index 76b38b5..e2fd3cf 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -116,6 +116,21 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3dcaa9ae7725d12cdb85b3ad99a434db70b468c09ded17e012d86b5c1010f7a7"
 
+[[package]]
+name = "futures"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e05b85ec287aac0dc34db7d4a569323df697f9c55b99b15d6b4ef8cde49f613"
+dependencies = [
+ "futures-channel",
+ "futures-core",
+ "futures-executor",
+ "futures-io",
+ "futures-sink",
+ "futures-task",
+ "futures-util",
+]
+
 [[package]]
 name = "futures-channel"
 version = "0.3.5"
@@ -123,6 +138,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f366ad74c28cca6ba456d95e6422883cfb4b252a83bed929c83abfdbbf2967d5"
 dependencies = [
  "futures-core",
+ "futures-sink",
 ]
 
 [[package]]
@@ -131,6 +147,35 @@ version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "59f5fff90fd5d971f936ad674802482ba441b6f09ba5e15fd8b39145582ca399"
 
+[[package]]
+name = "futures-executor"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10d6bb888be1153d3abeb9006b11b02cf5e9b209fda28693c31ae1e4e012e314"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "futures-util",
+]
+
+[[package]]
+name = "futures-io"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de27142b013a8e869c14957e6d2edeef89e97c289e69d042ee3a49acd8b51789"
+
+[[package]]
+name = "futures-macro"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0b5a30a4328ab5473878237c447333c093297bded83a4983d10f4deea240d39"
+dependencies = [
+ "proc-macro-hack",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "futures-sink"
 version = "0.3.5"
@@ -142,6 +187,9 @@ name = "futures-task"
 version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bdb66b5f09e22019b1ab0830f7785bcea8e7a42148683f99214f73f8ec21a626"
+dependencies = [
+ "once_cell",
+]
 
 [[package]]
 name = "futures-util"
@@ -149,10 +197,18 @@ version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8764574ff08b701a084482c3c7031349104b07ac897393010494beaa18ce32c6"
 dependencies = [
+ "futures-channel",
  "futures-core",
+ "futures-io",
+ "futures-macro",
+ "futures-sink",
  "futures-task",
+ "memchr",
  "pin-project",
  "pin-utils",
+ "proc-macro-hack",
+ "proc-macro-nested",
+ "slab",
 ]
 
 [[package]]
@@ -170,7 +226,9 @@ dependencies = [
 name = "gh-stack"
 version = "0.1.0"
 dependencies = [
+ "futures",
  "reqwest",
+ "serde",
  "tokio",
 ]
 
@@ -472,6 +530,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b631f7e854af39a1739f401cf34a8a013dfe09eac4fa4dba91e9768bd28168d"
+
 [[package]]
 name = "openssl"
 version = "0.10.29"
@@ -555,6 +619,18 @@ version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "237a5ed80e274dbc66f86bd59c1e25edc039660be53194b5fe0a482e0f2612ea"
 
+[[package]]
+name = "proc-macro-hack"
+version = "0.5.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e0456befd48169b9f13ef0f0ad46d492cf9d2dbb918bcf38e01eed4ce3ec5e4"
+
+[[package]]
+name = "proc-macro-nested"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e946095f9d3ed29ec38de908c22f95d9ac008e424c7bcae54c75a79c527c694"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.18"
@@ -708,6 +784,20 @@ name = "serde"
 version = "1.0.111"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c9124df5b40cbd380080b2cc6ab894c040a3070d995f5c9dc77e18c34a8ae37d"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.111"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f2c3ac8e6ca1e9c80b8be1023940162bf81ae3cffbb1809474152f2ce1eb250"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
 
 [[package]]
 name = "serde_json"
diff --git a/Cargo.toml b/Cargo.toml
index b1e9292..e15f57b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,3 +9,5 @@ edition = "2018"
 [dependencies]
 reqwest = { version = "0.10.6", features = ["json"] }
 tokio = { version = "0.2", features = ["full"] }
+serde = { version = "1.0", features = ["derive"] }
+futures = "0.3.5"
diff --git a/src/api/mod.rs b/src/api/mod.rs
index e092c24..41f6bd8 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -1 +1,13 @@
-pub mod search;
\ No newline at end of file
+use crate::Credentials;
+use reqwest::{Client, RequestBuilder};
+use std::time::Duration;
+
+pub mod search;
+
+fn base_request(client: &Client, credentials: &Credentials, url: &str) -> RequestBuilder {
+    client
+        .get(url)
+        .timeout(Duration::from_secs(5))
+        .header("Authorization", format!("token {}", credentials.token))
+        .header("User-Agent", "timothyandrew/gh-stack")
+}
diff --git a/src/api/search.rs b/src/api/search.rs
index 2e5122c..4830baa 100644
--- a/src/api/search.rs
+++ b/src/api/search.rs
@@ -1,18 +1,75 @@
+use futures::future::join_all;
+use serde::Deserialize;
 use std::error::Error;
 
-use crate::Credentials;
+use crate::{api, Credentials};
+
+#[derive(Deserialize, Debug)]
+pub struct SearchItem {
+    url: String,
+    title: String,
+}
+
+#[derive(Deserialize, Debug)]
+pub struct PullRequestRef {
+    label: String,
+    r#ref: String,
+    sha: String,
+}
+
+#[derive(Deserialize, Debug)]
+pub struct PullRequest {
+    id: usize,
+    head: PullRequestRef,
+    base: PullRequestRef,
+    title: String,
+}
+
+impl PullRequest {
+    pub fn head(&self) -> &str {
+        &self.head.label
+    }
+
+    pub fn base(&self) -> &str {
+        &self.base.label
+    }
+}
+
+#[derive(Deserialize, Debug)]
+struct SearchResponse {
+    items: Vec<SearchItem>,
+}
 
 pub async fn fetch_pull_requests_matching(
-  pattern: &str,
-  credentials: &Credentials,
-) -> Result<(), Box<dyn Error>> {
-  let client = reqwest::Client::new();
-  let request = client
-      .get("https://api.github.com/search/issues")
-      .query(&[("q", format!("{} in:title", pattern))])
-      .header("Authorization", format!("token {}", credentials.token))
-      .header("User-Agent", "timothyandrew/gh-stack");
-  let response = request.send().await?.text().await?;
-  println!("{}", response);
-  Ok(())
-}
\ No newline at end of file
+    pattern: &str,
+    credentials: &Credentials,
+) -> Result<Vec<PullRequest>, Box<dyn Error>> {
+    let client = reqwest::Client::new();
+
+    let request = api::base_request(
+        &client,
+        &credentials,
+        "https://api.github.com/search/issues",
+    )
+    .query(&[("q", format!("{} in:title", pattern))]);
+
+    let items = request.send().await?.json::<SearchResponse>().await?.items;
+
+    let item_futures = items.into_iter().map(|item| {
+        api::base_request(&client, &credentials, &item.url.replace("issues", "pulls")).send()
+    });
+
+    // The `unwrap`s are required here because both `reqwest::send` and `reqwest::json` return a `Result` which has
+    // to be unwrapped after the future has been `await`ed on.
+    let items = join_all(item_futures)
+        .await
+        .into_iter()
+        .map(|item| item.unwrap());
+    let responses: Vec<_> = join_all(items.map(|item| item.json::<PullRequest>()))
+        .await
+        .into_iter()
+        .map(|item| item.unwrap())
+        .collect();
+
+    Ok(responses)
+}
diff --git a/src/graph.rs b/src/graph.rs
new file mode 100644
index 0000000..e871e40
--- /dev/null
+++ b/src/graph.rs
@@ -0,0 +1,34 @@
+use std::collections::{HashMap, HashSet};
+
+use crate::api::search::PullRequest;
+
+pub fn build(prs: &[PullRequest]) {
+    let mut heads = HashSet::new();
+    let mut prs_by_base = HashMap::new();
+
+    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);
+        }
+    }
+    
+    results
+}
diff --git a/src/lib.rs b/src/lib.rs
index 7c5472e..841d60f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,5 @@
-
 pub mod api;
+pub mod graph;
 
 pub struct Credentials {
     // Personal access token
diff --git a/src/main.rs b/src/main.rs
index a816fee..7d2dd50 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,9 +1,10 @@
-use std::error::Error;
-use std::env;
 use std::collections::HashMap;
+use std::env;
+use std::error::Error;
 use std::process;
 
 use gh_stack::api;
+use gh_stack::graph;
 use gh_stack::Credentials;
 
 #[tokio::main]
@@ -17,10 +18,14 @@ async fn main() -> Result<(), Box<dyn Error>> {
     }
 
     let pattern = args.last().unwrap();
-    let token = env.get("GHSTACK_OAUTH_TOKEN").expect("You didn't pass `GHSTACK_OAUTH_TOKEN`");
+    let token = env
+        .get("GHSTACK_OAUTH_TOKEN")
+        .expect("You didn't pass `GHSTACK_OAUTH_TOKEN`");
 
     let credentials = Credentials::new(token);
-    api::search::fetch_pull_requests_matching(&pattern, &credentials).await?;
+
+    let prs = api::search::fetch_pull_requests_matching(&pattern, &credentials).await?;
+    graph::build(&prs);
 
     Ok(())
     /*