diff --git a/alethzero/Main.ui b/alethzero/Main.ui
index a1196acae..5886554e3 100644
--- a/alethzero/Main.ui
+++ b/alethzero/Main.ui
@@ -154,6 +154,7 @@
     <addaction name="debugStep"/>
     <addaction name="paranoia"/>
     <addaction name="killBlockchain"/>
+    <addaction name="inject"/>
    </widget>
    <addaction name="menu_File"/>
    <addaction name="menu_Network"/>
@@ -1045,6 +1046,11 @@
     <string>&amp;Export Selected Key...</string>
    </property>
   </action>
+  <action name="inject">
+   <property name="text">
+    <string>&amp;Inject Transaction</string>
+   </property>
+  </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
  <customwidgets>
diff --git a/alethzero/MainWin.cpp b/alethzero/MainWin.cpp
index 630006698..96ef45e2d 100644
--- a/alethzero/MainWin.cpp
+++ b/alethzero/MainWin.cpp
@@ -673,6 +673,14 @@ void Main::ourAccountsRowsMoved()
 	m_myKeys = myKeys;
 }
 
+void Main::on_inject_triggered()
+{
+	QString s = QInputDialog::getText(this, "Inject Transaction", "Enter transaction dump in hex");
+	bytes b = fromHex(s.toStdString());
+	m_client->inject(&b);
+	refresh();
+}
+
 void Main::on_blocks_currentItemChanged()
 {
 	ui->info->clear();
@@ -727,6 +735,10 @@ void Main::on_blocks_currentItemChanged()
 			s << "&nbsp;&emsp;&nbsp;#<b>" << tx.nonce << "</b>";
 			s << "<br/>Gas price: <b>" << formatBalance(tx.gasPrice) << "</b>";
 			s << "<br/>Gas: <b>" << tx.gas << "</b>";
+			s << "<br/>V: <b>" << hex << (int)tx.vrs.v << "</b>";
+			s << "<br/>R: <b>" << hex << tx.vrs.r << "</b>";
+			s << "<br/>S: <b>" << hex << tx.vrs.s << "</b>";
+			s << "<br/>Msg: <b>" << tx.sha3(false) << "</b>";
 			if (tx.isCreation())
 			{
 				if (tx.data.size())
@@ -747,7 +759,7 @@ void Main::on_blocks_currentItemChanged()
 void Main::on_contracts_currentItemChanged()
 {
 	ui->contractInfo->clear();
-	m_client->lock();
+	eth::ClientGuard l(&*m_client);
 	if (auto item = ui->contracts->currentItem())
 	{
 		auto hba = item->data(Qt::UserRole).toByteArray();
@@ -761,7 +773,6 @@ void Main::on_contracts_currentItemChanged()
 		s << "<h4>Body Code</h4>" << disassemble(state().code(h));
 		ui->contractInfo->appendHtml(QString::fromStdString(s.str()));
 	}
-	m_client->unlock();
 }
 
 void Main::on_idealPeers_valueChanged()
@@ -1033,7 +1044,7 @@ void Main::on_send_clicked()
 {
 	debugFinished();
 	u256 totalReq = value() + fee();
-	m_client->lock();
+	eth::ClientGuard l(&*m_client);
 	for (auto i: m_myKeys)
 		if (m_client->state().balance(i.address()) >= totalReq)
 		{
@@ -1046,7 +1057,6 @@ void Main::on_send_clicked()
 			refresh();
 			return;
 		}
-	m_client->unlock();
 	statusBar()->showMessage("Couldn't make transaction: no single account contains at least the required amount.");
 }
 
@@ -1054,7 +1064,7 @@ void Main::on_debug_clicked()
 {
 	debugFinished();
 	u256 totalReq = value() + fee();
-	m_client->lock();
+	eth::ClientGuard l(&*m_client);
 	for (auto i: m_myKeys)
 		if (m_client->state().balance(i.address()) >= totalReq)
 		{
@@ -1088,7 +1098,6 @@ void Main::on_debug_clicked()
 			updateDebugger();
 			return;
 		}
-	m_client->unlock();
 	statusBar()->showMessage("Couldn't make transaction: no single account contains at least the required amount.");
 }
 
diff --git a/alethzero/MainWin.h b/alethzero/MainWin.h
index b5a22671e..1258bac67 100644
--- a/alethzero/MainWin.h
+++ b/alethzero/MainWin.h
@@ -79,6 +79,7 @@ private slots:
 	void on_killBlockchain_triggered();
 	void on_importKey_triggered();
 	void on_exportKey_triggered();
+	void on_inject_triggered();
 
 	void refresh(bool _override = false);
 	void refreshNetwork();
diff --git a/libethcore/TrieDB.h b/libethcore/TrieDB.h
index 35aecdcb7..dd8a36fd5 100644
--- a/libethcore/TrieDB.h
+++ b/libethcore/TrieDB.h
@@ -61,6 +61,8 @@ inline std::ostream& operator<<(std::ostream& _out, BasicMap const& _m)
 	return _out;
 }
 
+class InvalidTrie: public std::exception {};
+
 class Overlay: public BasicMap
 {
 public:
@@ -196,8 +198,7 @@ public:
 						cdebug << rlp;
 						auto c = rlp.itemCount();
 						cdebug << c;
-						m_that = nullptr;
-						return;
+						throw InvalidTrie();
 						assert(rlp.isList() && (rlp.itemCount() == 2 || rlp.itemCount() == 17));
 					}
 					if (rlp.itemCount() == 2)
diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index 6f9c7e202..99cae63a1 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -174,6 +174,13 @@ Address Client::transact(Secret _secret, u256 _endowment, bytes const& _init, u2
 	return right160(sha3(rlpList(t.sender(), t.nonce)));
 }
 
+void Client::inject(bytesConstRef _rlp)
+{
+	lock_guard<recursive_mutex> l(m_lock);
+	m_tq.attemptImport(_rlp);
+	m_changed = true;
+}
+
 void Client::work()
 {
 	bool changed = false;
diff --git a/libethereum/Client.h b/libethereum/Client.h
index e9cc845df..bb3e3a2ce 100644
--- a/libethereum/Client.h
+++ b/libethereum/Client.h
@@ -90,6 +90,8 @@ public:
 	/// @returns the new contract's address (assuming it all goes through).
 	Address transact(Secret _secret, u256 _endowment, bytes const& _init, u256 _gas = 10000, u256 _gasPrice = 10 * szabo);
 
+	void inject(bytesConstRef _rlp);
+
 	/// Makes the given call. Nothing is recorded into the state. TODO
 //	bytes call(Secret _secret, u256 _amount, u256 _gasPrice, Address _dest, u256 _gas, bytes _data = bytes());
 
diff --git a/libethereum/Executive.cpp b/libethereum/Executive.cpp
index d3147cb04..a8bd3a86e 100644
--- a/libethereum/Executive.cpp
+++ b/libethereum/Executive.cpp
@@ -108,6 +108,11 @@ void Executive::call(Address _receiveAddress, Address _senderAddress, u256 _valu
 
 void Executive::create(Address _sender, u256 _endowment, u256 _gasPrice, u256 _gas, bytesConstRef _init, Address _origin)
 {
+#if ETH_PARANOIA
+
+
+#endif
+
 	m_newAddress = right160(sha3(rlpList(_sender, m_s.transactionsFrom(_sender) - 1)));
 	while (m_s.addressInUse(m_newAddress))
 		m_newAddress = (u160)m_newAddress + 1;
diff --git a/libethereum/PeerServer.cpp b/libethereum/PeerServer.cpp
index 8b3644aa5..6a79f9f35 100644
--- a/libethereum/PeerServer.cpp
+++ b/libethereum/PeerServer.cpp
@@ -363,7 +363,7 @@ bool PeerServer::sync(BlockChain& _bc, TransactionQueue& _tq, Overlay& _o)
 	if (m_mode == NodeMode::Full)
 	{
 		for (auto it = m_incomingTransactions.begin(); it != m_incomingTransactions.end(); ++it)
-			if (_tq.import(*it))
+			if (_tq.import(&*it))
 			{}//ret = true;		// just putting a transaction in the queue isn't enough to change the state - it might have an invalid nonce...
 			else
 				m_transactionsSent.insert(sha3(*it));	// if we already had the transaction, then don't bother sending it on.
diff --git a/libethereum/State.cpp b/libethereum/State.cpp
index 72ad36346..ac605644f 100644
--- a/libethereum/State.cpp
+++ b/libethereum/State.cpp
@@ -158,14 +158,9 @@ struct CachedAddressState
 		std::map<u256, u256> ret;
 		if (r)
 		{
-			cdebug << "MemDB: " << r[2].toHash<h256>();
 			TrieDB<h256, Overlay> memdb(const_cast<Overlay*>(o), r[2].toHash<h256>());		// promise we won't alter the overlay! :)
-			cdebug << memdb.root();
 			for (auto const& j: memdb)
-			{
-				cdebug << j.first;
 				ret[j.first] = RLP(j.second).toInt<u256>();
-			}
 		}
 		if (s)
 			for (auto const& j: s->storage())
@@ -859,13 +854,16 @@ u256 State::execute(bytesConstRef _rlp)
 	commit();	// get an updated hash
 #endif
 
+	// TODO: CHECK TRIE
+
 	State old(*this);
 	auto h = rootHash();
 
 	Executive e(*this);
 	e.setup(_rlp);
 
-	cnote << "Executing " << e.t() << "on" << h;
+	cnote << "Executing" << e.t() << "on" << h;
+	cnote << toHex(e.t().rlp(true));
 
 	u256 startGasUsed = gasUsed();
 	if (startGasUsed + e.t().gas > m_currentBlock.gasLimit)
@@ -882,6 +880,9 @@ u256 State::execute(bytesConstRef _rlp)
 	cnote << "Executed; now" << rootHash();
 	cnote << old.diff(*this);
 
+	// TODO: CHECK TRIE
+	// TODO: CHECK TRIE after level DB flush to make sure exactly the same.
+
 	// Add to the user-originated transactions that we've executed.
 	m_transactions.push_back(TransactionReceipt(e.t(), rootHash(), startGasUsed + e.gasUsed()));
 	m_transactionSet.insert(e.t().sha3());
diff --git a/libethereum/TransactionQueue.cpp b/libethereum/TransactionQueue.cpp
index 3eb6a347b..7ff7a174e 100644
--- a/libethereum/TransactionQueue.cpp
+++ b/libethereum/TransactionQueue.cpp
@@ -27,7 +27,7 @@
 using namespace std;
 using namespace eth;
 
-bool TransactionQueue::import(bytes const& _block)
+bool TransactionQueue::import(bytesConstRef _block)
 {
 	// Check if we already know this transaction.
 	h256 h = sha3(_block);
@@ -44,7 +44,7 @@ bool TransactionQueue::import(bytes const& _block)
 			m_interestQueue.push_back(t);
 
 		// If valid, append to blocks.
-		m_data[h] = _block;
+		m_data[h] = _block.toBytes();
 	}
 	catch (InvalidTransactionFormat const& _e)
 	{
diff --git a/libethereum/TransactionQueue.h b/libethereum/TransactionQueue.h
index 3736f392c..e42da52b7 100644
--- a/libethereum/TransactionQueue.h
+++ b/libethereum/TransactionQueue.h
@@ -35,8 +35,9 @@ class BlockChain;
 class TransactionQueue
 {
 public:
-	bool attemptImport(bytes const& _block) { try { import(_block); return true; } catch (...) { return false; } }
-	bool import(bytes const& _block);
+	bool attemptImport(bytesConstRef _block) { try { import(_block); return true; } catch (...) { return false; } }
+	bool attemptImport(bytes const& _block) { try { import(&_block); return true; } catch (...) { return false; } }
+	bool import(bytesConstRef _block);
 	void drop(h256 _txHash) { m_data.erase(_txHash); }
 	std::map<h256, bytes> const& transactions() const { return m_data; }