We are a team of 6 in a room and the project was being held back because our progress was behind the projected schedule by the boss. One team member is off work for two weeks for family reasons and another team member fell ill 2 days back, the four of us are putting in overtime to pull through, we are even working after returning home and barely get time to have food. This morning our boss called us up and said he didn't care how, we needed to complete our part by end of day. We got 2 of our friends to help us out, but when we still werent done by end of day, our boss came and locked the room and said he won't let us out unless the work is done. We felt really bad for the two friends whom we called up to help us and got stuck with us. The 6 of us somehow finished the work after hours, told the boss via call and somehow left for home after the watchman came and unlocked the room on his orders.

I am baffled by this behaviour. Surely this has to be illegal?

P.s. we didn't even get paid for the overtime we put in because apparently " it's not accounted in the project budget"

P.p.s. if you're wondering what company it is, it's a company owned by Larsen and Toubro.

Edit 1: I am not making a huge scene of this and going to police or media as it would most likely cause me to be fired and I don't have another offer in hand to fall back on. My family is kinda in debt, so I wanna contribute as much as possible. Plus it may put a trouble maker tag on me which can reduce my future job prospects. I will be shifted to a different team at another location by the end of this month, so it's just about tolerating him for this duration and I don't think it's worth risking my career for.

Edit 2: no I didn't take videographic evidence of the fact but I do have some time stamped photos. Reason being I didn't wanna piss him off even further and cause him to retaliate in other ways.

Edit 3: Yes I am looking for other opportunities to move out of here ASAP, talking with other people who have been here for a few years paints a bleak picture for me, very less increment, slow promotion and often uncompensated overtime. I have been looking for other jobs for a while but haven't managed to get any so far, probably because I am a fresher and I don't have much experience plus from a tier 3 government college.