Here's your 10-point cheatsheet to this big story:
The cricketer-turned-politician tweeted a resignation letter that hinted at his unhappiness at the ongoing changes to the Punjab cabinet. "The collapse of a man's character stems from the compromise corner. I can never compromise on Punjab's future and the agenda for the welfare of Punjab. Therefore, I hereby resign as the President of Punjab Pradesh Congress Committee. I will continue to serve the Congress," Navjot Sidhu, 57, wrote in his letter to Sonia Gandhi, which he posted on social media. He had taken charge of the party in Punjab in July.
Sources say Mr Sidhu was upset about the cabinet changes made by new Chief Minister Charanjit Singh Channi, who was seen to be close to him. Though Mr Sidhu was widely seen to act as "Super Chief Minister" when it came to some decisions, he was reportedly ignored in recent appointments seen as controversial. He was also angry about key posts given to officials linked to the "sacrilege" case.
Navjot Sidhu, say sources, was also unhappy about his rival SS Randhawa being assigned a key ministry. The double use of the word "compromise" in Mr Sidhu's resignation letter was read as a clue that he was asked to accept some unpleasant choices in the cabinet shuffle.
Amarinder Singh, recently replaced as Chief Minister at Navjot Sidhu's instance, did not lose time in posting an "I-told-you-so" for the Congress leadership. "I told you so...he is not a stable man and not fit for the border state of Punjab," tweeted the former Chief Minister, who is believed to be closing in on his own decision on his future in the Congress.
With the top two Congress faces in the state exiting in this manner, Punjab has become Exhibit A in the party's growing disarray. The Congress's loss could well be Arvind Kejriwal's gain; his Aam Aadmi Party (AAP) is campaigning aggressively in Punjab and Mr Kejriwal will also visit the state on Wednesday. Mr Sidhu's resignation, four months before the Punjab election, calls to question a series of decisions by the leadership.
Merely two days after she took oath of office as a cabinet minister in the Punjab government, Malerkotla MLA Razia Sultana, on Tuesday, resigned "in solidarity with Navjot Singh Sidhu". "Sidhu sahab is a man of principles. He is fighting for Punjab and Punjabiyat," Ms Sultana said. Punjab Congress General Secretary Yoginder Dhingra and treasurer Gulzar Inder Chahal followed with their resignations.
The Punjab cabinet met on Tuesday evening on the crisis and will meet again on Wednesday morning in Chandigarh. Punjab Congress General Secretary Pargat Singh has been asked to pacify Mr Sidhu, who is currently at this house in Patiala, sources said. "Nothing to worry, everything will be alright," Congress leader KC Venugopal said over the resignations in "solidarity" with Mr Sidhu.
Mr Sidhu's adviser Surinder Dalla said the Congress leader has "no personal rivalry with Amarinder Singh". "The new government should have made careful decisions and addressed issues since Day 1. It should have followed the party line," Mr Dalla told NDTV. "I can't say whether Mr Sidhu would withdraw his resignation," he said.
Despite warnings, Priyanka Gandhi Vadra had pushed strongly for Mr Sidhu and had even arranged his meeting with Rahul Gandhi when the Congress was trying to decide on what to do about Amarinder Singh. The Punjab crisis has smacked the party on a day it welcomed on board high profile faces like Kanhaiya Kumar and Jignesh Mevani.
Mr Sidhu's move coincides with Amarinder Singh's visit to Delhi Tuesday. Though it is described as "personal", there is speculation about a possible meeting between the Captain and the BJP. Amarinder Singh resigned as Chief Minister 10 days ago, complaining of repeated "humiliation" by the party. Mr Sidhu, who set the stage for his exit, has now himself quit his post, though he says he will "continue to serve the Congress".