diff --git a/zebrad/src/commands/start.rs b/zebrad/src/commands/start.rs
index 5109e774..39817b3b 100644
--- a/zebrad/src/commands/start.rs
+++ b/zebrad/src/commands/start.rs
@@ -1,46 +1,42 @@
-//! `start` subcommand - example of how to write a subcommand
-
-/// App-local prelude includes `app_reader()`/`app_writer()`/`app_config()`
-/// accessors along with logging macros. Customize as you see fit.
-use crate::prelude::*;
-
+//! `start` subcommand - entry point for starting a zebra node
 use crate::config::ZebradConfig;
-
+use crate::{components::tokio::TokioComponent, prelude::*};
 use abscissa_core::{config, Command, FrameworkError, Options, Runnable};
+use color_eyre::Report;
+use eyre::{eyre, WrapErr};
+use futures::{
+    prelude::*,
+    stream::{FuturesUnordered, StreamExt},
+};
+use std::collections::BTreeSet;
+use tower::{buffer::Buffer, service_fn, Service, ServiceExt};
+use zebra_chain::{block::BlockHeaderHash, types::BlockHeight};
 
-use futures::prelude::*;
+// genesis
+static GENESIS: BlockHeaderHash = BlockHeaderHash([
+    8, 206, 61, 151, 49, 176, 0, 192, 131, 56, 69, 92, 138, 74, 107, 208, 93, 161, 110, 38, 177,
+    29, 170, 27, 145, 113, 132, 236, 232, 15, 4, 0,
+]);
 
 /// `start` subcommand
-///
-/// The `Options` proc macro generates an option parser based on the struct
-/// definition, and is defined in the `gumdrop` crate. See their documentation
-/// for a more comprehensive example:
-///
-/// <https://docs.rs/gumdrop/>
 #[derive(Command, Debug, Options)]
 pub struct StartCmd {
     /// Filter strings
     #[options(free)]
     filters: Vec<String>,
+
+    /// The address of the node to connect to.
+    #[options(
+        help = "The address of the node to connect to.",
+        default = "127.0.0.1:8233"
+    )]
+    addr: std::net::SocketAddr,
 }
 
 impl Runnable for StartCmd {
     /// Start the application.
     fn run(&self) {
-        warn!("starting application");
-        let config = app_config();
-        if let Some(filter) = &config.tracing.filter {
-            println!("filter: {}!", filter);
-        }
-
-        let default_config = ZebradConfig::default();
-        println!("Default config: {:?}", default_config);
-
-        println!("Toml:\n{}", toml::Value::try_from(&default_config).unwrap());
-
-        info!("Starting placeholder loop");
-
-        use crate::components::tokio::TokioComponent;
+        info!(connect.addr = ?self.addr);
 
         let rt = app_writer()
             .state_mut()
@@ -50,8 +46,17 @@ impl Runnable for StartCmd {
             .rt
             .take();
 
-        rt.expect("runtime should not already be taken")
-            .block_on(future::pending::<()>());
+        let result = rt
+            .expect("runtime should not already be taken")
+            .block_on(self.connect());
+
+        match result {
+            Ok(()) => {}
+            Err(e) => {
+                eprintln!("Error: {:?}", e);
+                std::process::exit(1);
+            }
+        }
     }
 }
 
@@ -67,3 +72,163 @@ impl config::Override<ZebradConfig> for StartCmd {
         Ok(config)
     }
 }
+
+impl StartCmd {
+    async fn connect(&self) -> Result<(), Report> {
+        info!(?self, "begin tower-based peer handling test stub");
+
+        // The service that our node uses to respond to requests by peers
+        let node = Buffer::new(
+            service_fn(|req| async move {
+                info!(?req);
+                Ok::<zebra_network::Response, Report>(zebra_network::Response::Nil)
+            }),
+            1,
+        );
+
+        let mut config = app_config().network.clone();
+        // Use a different listen addr so that we don't conflict with another local node.
+        config.listen_addr = "127.0.0.1:38233".parse()?;
+        // Connect only to the specified peer.
+        config.initial_mainnet_peers.insert(self.addr.to_string());
+
+        let state = zebra_state::in_memory::init();
+        let (peer_set, _address_book) = zebra_network::init(config, node).await;
+        let retry_peer_set = tower::retry::Retry::new(zebra_network::RetryErrors, peer_set.clone());
+
+        let mut downloaded_block_heights = BTreeSet::<BlockHeight>::new();
+        downloaded_block_heights.insert(BlockHeight(0));
+
+        let mut connect = Start {
+            retry_peer_set,
+            peer_set,
+            state,
+            tip: GENESIS,
+            block_requests: FuturesUnordered::new(),
+            requested_block_heights: 0,
+            downloaded_block_heights,
+        };
+
+        connect.connect().await
+    }
+}
+
+struct Start<ZN, ZS>
+where
+    ZN: Service<zebra_network::Request>,
+{
+    retry_peer_set: tower::retry::Retry<zebra_network::RetryErrors, ZN>,
+    peer_set: ZN,
+    state: ZS,
+    tip: BlockHeaderHash,
+    block_requests: FuturesUnordered<ZN::Future>,
+    requested_block_heights: usize,
+    downloaded_block_heights: BTreeSet<BlockHeight>,
+}
+
+impl<ZN, ZS> Start<ZN, ZS>
+where
+    ZN: Service<zebra_network::Request, Response = zebra_network::Response, Error = Error>
+        + Send
+        + Clone
+        + 'static,
+    ZN::Future: Send,
+    ZS: Service<zebra_state::Request, Response = zebra_state::Response, Error = Error>
+        + Send
+        + Clone
+        + 'static,
+    ZS::Future: Send,
+{
+    async fn connect(&mut self) -> Result<(), Report> {
+        // TODO(jlusby): Replace with real state service
+
+        while self.requested_block_heights < 700_000 {
+            let hashes = self.next_hashes().await?;
+            self.tip = *hashes.last().unwrap();
+
+            // Request the corresponding blocks in chunks
+            self.request_blocks(hashes).await?;
+
+            // Allow at most 300 block requests in flight.
+            self.drain_requests(300).await?;
+        }
+
+        self.drain_requests(0).await?;
+
+        let eternity = future::pending::<()>();
+        eternity.await;
+
+        Ok(())
+    }
+
+    async fn next_hashes(&mut self) -> Result<Vec<BlockHeaderHash>, Report> {
+        // Request the next 500 hashes.
+        self.retry_peer_set
+            .ready_and()
+            .await
+            .map_err(|e| eyre!(e))?
+            .call(zebra_network::Request::FindBlocks {
+                known_blocks: vec![self.tip],
+                stop: None,
+            })
+            .await
+            .map_err(|e| eyre!(e))
+            .wrap_err("request failed, TODO implement retry")
+            .map(|response| match response {
+                zebra_network::Response::BlockHeaderHashes(hashes) => hashes,
+                _ => unreachable!("FindBlocks always gets a BlockHeaderHashes response"),
+            })
+            .map(|hashes| {
+                info!(
+                    new_hashes = hashes.len(),
+                    requested = self.requested_block_heights,
+                    in_flight = self.block_requests.len(),
+                    downloaded = self.downloaded_block_heights.len(),
+                    highest = self.downloaded_block_heights.iter().next_back().unwrap().0,
+                    "requested more hashes"
+                );
+                self.requested_block_heights += hashes.len();
+                hashes
+            })
+    }
+
+    async fn request_blocks(&mut self, hashes: Vec<BlockHeaderHash>) -> Result<(), Report> {
+        for chunk in hashes.chunks(10usize) {
+            let request = self.peer_set.ready_and().await.map_err(|e| eyre!(e))?.call(
+                zebra_network::Request::BlocksByHash(chunk.iter().cloned().collect()),
+            );
+
+            self.block_requests.push(request);
+        }
+
+        Ok(())
+    }
+
+    async fn drain_requests(&mut self, request_goal: usize) -> Result<(), Report> {
+        while self.block_requests.len() > request_goal {
+            match self.block_requests.next().await {
+                Some(Ok(zebra_network::Response::Blocks(blocks))) => {
+                    for block in blocks {
+                        self.downloaded_block_heights
+                            .insert(block.coinbase_height().unwrap());
+                        self.state
+                            .ready_and()
+                            .await
+                            .map_err(|e| eyre!(e))?
+                            .call(zebra_state::Request::AddBlock { block })
+                            .await
+                            .map_err(|e| eyre!(e))?;
+                    }
+                }
+                Some(Err(e)) => {
+                    error!(%e);
+                }
+                _ => continue,
+            }
+        }
+
+        Ok(())
+    }
+}
+
+type Error = Box<dyn std::error::Error + Send + Sync + 'static>;