Could there be an effort to censure the PM?
Rather to its own surprise, Parliament is back in action...
But having been summoned back to scrutinise Brexit, there's not much Brexiting to scrutinise and MPs and peers will instead face a series of legislative chores, with only one major piece of legislation, the Domestic Abuse Bill, in play.
There's a certain element of "pick up sticks and lay them straight" about the agenda in both houses, but keep an eye out for unscheduled business - urgent questions will certainly drop into the agenda, and later in the week it is possible there might be some further attempt by backbench Remainers to seize control of Commons business.
Such manoeuvres seem unlikely while the Conservative conference is in play - it would look like a dirty trick to try and push something through while many ministers and Conservative MPs were hours away in Manchester, and it might invite retaliation against future opposition party conferences later.
At the moment an attempt to no-confidence the government looks unlikely, on the argument that it would get in the way of securing a further Brexit postponement, but there could be some effort to censure the PM or demand key documents from the failed prorogation, or some move to head off an attempt to get round the Benn-Burt legislation which would otherwise force the PM to seek a postponement of Brexit.
This is all very speculative, but all I can really point to is the sight of conspiratorial little huddles all around Parliament, and the enigmatic smiles that greet any attempt to find out what the different factions are up to.
Elsewhere, it will be a pretty quiet week on the Committee Corridor. Since the Commons was not expected to be sitting, no meetings were arranged and the lead time for organising witnesses to come in has meant that few committee hearings could be arranged.
The exception is the ever-industrious Public Accounts Committee, which maintains its Stakhanovite reputation with two important-looking sessions, first on special educational needs and then on the supply of medicines after Brexit.
The other committee event to look out for is the hoped-for appearance by the prime minister before the Liaison Committee.
This is the super-committee of all the select committee chairs, which questions the PM at least twice every parliamentary session. Boris Johnson was due to make his debut appearance a couple of weeks ago, but it was forestalled by prorogation that never was.
The session, if it happens (and as I write there is no confirmation of any new date) will doubtless be dominated by Brexit, but there is one amusing sub-plot; what if the PM's chief adviser, Dominic Cummings turns up in his entourage?
Mr Cummings, remember, has been held in contempt of Parliament for his refusal to appear before the Digital, Culture, Media and Sport Committee, which is probing the allegations about the Vote Leave campaign in the 2016 referendum.
There's a strong view that it would be completely wrong for him to attend, while his contempt remains unpurged. So if he does turn up he would be ordered out - which could provide some interesting theatrics.
I imagine murmured warnings via the usual back-channels will prevent such a scene, but at the moment there seems to be a bit of a taste for drama.
Monday 30 September
In the Commons (14:30) MPs will deal with any urgent questions or ministerial statements before moving on to a series of Northern Ireland-related debates.
There is no departmental question time, because there has not been sufficient notice to put down questions - but there will have been by Tuesday, so the normal question times will then resume.
The Northern Ireland debates, required under the Northern Ireland (Executive Formation etc) Act, cover historical institutional abuse, victims' payment, human trafficking and gambling.
On the Committee Corridor, Public Accounts (16:00) takes evidence on the support for children with special educational needs and disabilities, based on this report from the financial watchdog, the National Audit Office.
The report concluded that while many pupils with SEND were receiving excellent support, many others were not - with serious consequences for their long-term prospects.
In the Lords (14:30) questions to ministers include the former chair of the Metropolitan Police Authority, Labour's Lord Harris of Haringey, asking when the additional 20,000 police officers promised by the prime minister will be deployed on duty.
The day's legislative business starts with the second reading debate for the Non-Domestic Rating (Lists) Bill - this would implement the government's commitment to alter the length of time between revaluations of rateable values for business rates, bringing the next revaluation forward a year, to 2021, in England and Wales.
It would also move the business rates revaluation cycle in England, from the present five-year cycle to a three-year cycle.
Peers will then be asked to approve statutory instruments on Human Medicines and Medical Devices and Insolvency Regulations.
Tuesday 1 October
Ministerial question times resume in the Commons (11:30) with Chancellor Sajid Javid at the despatch box.
The main listed business is a humdrum series of Brexit SIs, on common organisation of the markets in agricultural products, import and export licences and pesticides. So there will be plenty of scope for urgent questions and ministerial statements - although ministers might prefer to be making any big announcements at the Conservative conference in Manchester.
Debates also resume in Westminster Hall, with Conservative ex-minister Sir Christopher Chope continuing his long running campaign on the rights of people living in mobile homes (09:30), Bob Seeley leading a debate on improving healthcare on the Isle of Wight (11:00) and the former Lib Dem leader Sir Vince Cable discusses social care funding (14:30).
Other debates include Labour's Liz Kendall on child poverty in Leicester (16:00) and whipless ex-minister Margot James on adult learning and vocational skills training in Dudley (16:30).
In the Lords (14:30) Big Issue founder and crossbench peer Lord Bird has a question about taking into account the interests of future generations at every level of government policy-making
And then peers settle down to debate another mixed bag of orders and regulations.
Wednesday 2 October
Commons business opens (11:30) with international development questions, followed by prime minister's question time. This will probably not have Mr Johnson in the starring role, because he's expected to be addressing the Conservative Party conference.
The assumption is that Foreign Secretary, Dominic Raab, who is First Secretary of State, will deputise.
Next, Plaid Cymru MP Jonathan Edwards will present a Ten Minute Rule Bill to set up an advisory body on the share-out of government money across the UK.
The day's legislation is the biggest single thing on the week's parliamentary agenda; the second reading debate for the Domestic Abuse Bill - which was the major casualty of the abortive prorogation of Parliament. It has now sprung back to life and can begin its legislative journey.
The adjournment debate, led by Conservative MP Glyn Davies, is on the Welsh language.
In Westminster Hall, subjects for debate include the role of community pharmacies (09:30); proposed changes to free movement of EU nationals (11:00); trophy hunting imports (14:30); progress on leasehold and commonhold reform (16:00) and performance of child maintenance service in recovering payments from absent parents (16:30).
The Treasury Committee has an evidence session on the economic opportunities from decarbonisation and green finance (14:30.
The Public Accounts Committee (also 14:30) quizzes the top civil servant at the Department of Health and Social Care, Sir Chris Wormald, ands a supporting cast of senior officials about the availability of medicines and other medical supplies after Brexit, based on this report from the National Audit Office
In the Lords (15:00) questions to ministers include Lord Young of Cookham (the former transport secretary and later Leader of the Commons, Sir George Young) asking about the procedures followed in the dismissal of Sonia Khan as a special adviser - she was the media adviser to the chancellor, who was sacked and escorted out of Downing Street by an armed police officer. It was an incident that raised eyebrows in Whitehall.
Then Brexit minister Lord Callanan bats for the government in the overwhelmingly Remainer upper house, in a general debate on the UK's withdrawal from the EU.
Thursday 3 October
MPs begin (09:30) with digital, culture, media and sport questions - a despatch box debut in her new role for Nicky Morgan, followed by a mini-question time, but probably quite an entertaining one, for Attorney General Geoffrey Cox, fresh from his combative statement to MPs on the prorogation issue.
Tow general debates follow; first on a motion from the Lib Dem Vera Hobhouse on the rise of mental illness among women; then on the spending of the Ministry of Justice, led by the chair of the Justice Committee, Conservative Bob Neill.
In Westminster Hall (13:30) the chairman of the Foreign Affairs Committee, Tom Tugendhat, leads a debate on sanctions policy, following a report from his committee describing the current policy as "fragmented and incoherent."
In the Lords (11:00) the normal half hour of questions to ministers is followed by debates on subjects raised by backbench peers from the crossbenches.
The first is from former Chief Inspector of Prisons Lord Ramsbotham on reforming the management and treatment of offenders in prison and the community.
Then former Bishop of Oxford Lord Harries of Pentregarth has a debate on ensuring that human rights are respected in any future trade deals with other countries.
Neither House is expected to sit on Friday 4 October, but these days, you never know......